diff --git a/Marlin/Configuration.h b/Marlin/Configuration.h
index c933b6887c6c871b6a657c7d71e415f24de1bd42..25a2571549b8e38348d72c7cb8b82c6d0bf3b91f 100644
--- a/Marlin/Configuration.h
+++ b/Marlin/Configuration.h
@@ -108,8 +108,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 250000
 
diff --git a/Marlin/Configuration_adv.h b/Marlin/Configuration_adv.h
index fbab9b819118cf95e0eaea9c9386a8f3d33acb13..402c5b18cfb7d9ab50f6f857e1e5bfb265a1c2a4 100644
--- a/Marlin/Configuration_adv.h
+++ b/Marlin/Configuration_adv.h
@@ -751,7 +751,7 @@
 #define MAX_CMD_SIZE 96
 #define BUFSIZE 4
 
-// Transfer Buffer Size
+// Transmission to Host Buffer Size
 // To save 386 bytes of PROGMEM (and TX_BUFFER_SIZE+3 bytes of RAM) set to 0.
 // To buffer a simple "ok" you need 4 bytes.
 // For ADVANCED_OK (M105) you need 32 bytes.
@@ -760,6 +760,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 0
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410
diff --git a/Marlin/src/HAL/HAL_AVR/MarlinSerial.cpp b/Marlin/src/HAL/HAL_AVR/MarlinSerial.cpp
index 6e6430f77a73d8b41805e21aa1474318256bf187..ca83f24c02d815bd9d90adeaf29724d7bc9b9eb6 100644
--- a/Marlin/src/HAL/HAL_AVR/MarlinSerial.cpp
+++ b/Marlin/src/HAL/HAL_AVR/MarlinSerial.cpp
@@ -27,16 +27,31 @@
  * Modified 23 November 2006 by David A. Mellis
  * Modified 28 September 2010 by Mark Sproul
  * Modified 14 February 2016 by Andreas Hardtung (added tx buffer)
+ * Modified 01 October 2017 by Eduardo José Tagle (added XON/XOFF)
  */
 #ifdef __AVR__
 
-#include "MarlinSerial.h"
-#include "../../Marlin.h"
-
 // Disable HardwareSerial.cpp to support chips without a UART (Attiny, etc.)
 
+#include "../../inc/MarlinConfig.h"
+
 #if !defined(USBCON) && (defined(UBRRH) || defined(UBRR0H) || defined(UBRR1H) || defined(UBRR2H) || defined(UBRR3H))
 
+  #include "MarlinSerial.h"
+  #include "../../Marlin.h"
+
+  struct ring_buffer_r {
+    unsigned char buffer[RX_BUFFER_SIZE];
+    volatile ring_buffer_pos_t head, tail;
+  };
+
+  #if TX_BUFFER_SIZE > 0
+    struct ring_buffer_t {
+      unsigned char buffer[TX_BUFFER_SIZE];
+      volatile uint8_t head, tail;
+    };
+  #endif
+
   #if UART_PRESENT(SERIAL_PORT)
     ring_buffer_r rx_buffer = { { 0 }, 0, 0 };
     #if TX_BUFFER_SIZE > 0
@@ -45,6 +60,23 @@
     #endif
   #endif
 
+  #if ENABLED(SERIAL_XON_XOFF)
+    uint8_t xon_xoff_state = XON_XOFF_CHAR_SENT | XON_CHAR;
+    constexpr uint8_t XON_XOFF_CHAR_SENT = 0x80;  // XON / XOFF Character was sent
+    constexpr uint8_t XON_XOFF_CHAR_MASK = 0x1F;  // XON / XOFF character to send
+    // XON / XOFF character definitions
+    constexpr uint8_t XON_CHAR  = 17;
+    constexpr uint8_t XOFF_CHAR = 19;
+  #endif
+
+  #if ENABLED(SERIAL_STATS_DROPPED_RX)
+    uint8_t rx_dropped_bytes = 0;
+  #endif
+
+  #if ENABLED(SERIAL_STATS_MAX_RX_QUEUED)
+    ring_buffer_pos_t rx_max_enqueued = 0;
+  #endif
+
   #if ENABLED(EMERGENCY_PARSER)
 
     #include "../../module/stepper.h"
@@ -136,20 +168,78 @@
 
   #endif // EMERGENCY_PARSER
 
-  FORCE_INLINE void store_char(unsigned char c) {
-    CRITICAL_SECTION_START;
-      const uint8_t h = rx_buffer.head,
-                    i = (uint8_t)(h + 1) & (RX_BUFFER_SIZE - 1);
-
-      // if we should be storing the received character into the location
-      // just before the tail (meaning that the head would advance to the
-      // current location of the tail), we're about to overflow the buffer
-      // and so we don't write the character or advance the head.
-      if (i != rx_buffer.tail) {
-        rx_buffer.buffer[h] = c;
-        rx_buffer.head = i;
+  FORCE_INLINE void store_rxd_char() {
+    const ring_buffer_pos_t h = rx_buffer.head,
+                            i = (ring_buffer_pos_t)(h + 1) & (ring_buffer_pos_t)(RX_BUFFER_SIZE - 1);
+
+    // If the character is to be stored at the index just before the tail
+    // (such that the head would advance to the current tail), the buffer is
+    // critical, so don't write the character or advance the head.
+    if (i != rx_buffer.tail) {
+      rx_buffer.buffer[h] = M_UDRx;
+      rx_buffer.head = i;
+    }
+    else {
+      (void)M_UDRx;
+      #if ENABLED(SERIAL_STATS_DROPPED_RX)
+        if (!++rx_dropped_bytes) ++rx_dropped_bytes;
+      #endif
+    }
+
+    #if ENABLED(SERIAL_STATS_MAX_RX_QUEUED)
+      // calculate count of bytes stored into the RX buffer
+      ring_buffer_pos_t rx_count = (ring_buffer_pos_t)(rx_buffer.head - rx_buffer.tail) & (ring_buffer_pos_t)(RX_BUFFER_SIZE - 1);
+      // Keep track of the maximum count of enqueued bytes
+      NOLESS(rx_max_enqueued, rx_count);
+    #endif
+
+    #if ENABLED(SERIAL_XON_XOFF)
+
+      // for high speed transfers, we can use XON/XOFF protocol to do
+      // software handshake and avoid overruns.
+      if ((xon_xoff_state & XON_XOFF_CHAR_MASK) == XON_CHAR) {
+
+        // calculate count of bytes stored into the RX buffer
+        ring_buffer_pos_t rx_count = (ring_buffer_pos_t)(rx_buffer.head - rx_buffer.tail) & (ring_buffer_pos_t)(RX_BUFFER_SIZE - 1);
+
+        // if we are above 12.5% of RX buffer capacity, send XOFF before
+        // we run out of RX buffer space .. We need 325 bytes @ 250kbits/s to
+        // let the host react and stop sending bytes. This translates to 13mS
+        // propagation time.
+        if (rx_count >= (RX_BUFFER_SIZE) / 8) {
+          // If TX interrupts are disabled and data register is empty,
+          // just write the byte to the data register and be done. This
+          // shortcut helps significantly improve the effective datarate
+          // at high (>500kbit/s) bitrates, where interrupt overhead
+          // becomes a slowdown.
+          if (!TEST(M_UCSRxB, M_UDRIEx) && TEST(M_UCSRxA, M_UDREx)) {
+            // Send an XOFF character
+            M_UDRx = XOFF_CHAR;
+            // clear the TXC bit -- "can be cleared by writing a one to its bit
+            // location". This makes sure flush() won't return until the bytes
+            // actually got written
+            SBI(M_UCSRxA, M_TXCx);
+            // And remember it was sent
+            xon_xoff_state = XOFF_CHAR | XON_XOFF_CHAR_SENT;
+          }
+          else {
+            // TX interrupts disabled, but buffer still not empty ... or
+            // TX interrupts enabled. Reenable TX ints and schedule XOFF
+            // character to be sent
+            #if TX_BUFFER_SIZE > 0
+              SBI(M_UCSRxB, M_UDRIEx);
+              xon_xoff_state = XOFF_CHAR;
+            #else
+              // We are not using TX interrupts, we will have to send this manually
+              while (!TEST(M_UCSRxA, M_UDREx)) { /* nada */ };
+              M_UDRx = XOFF_CHAR;
+              // And remember we already sent it
+              xon_xoff_state = XOFF_CHAR | XON_XOFF_CHAR_SENT;
+            #endif
+          }
+        }
       }
-    CRITICAL_SECTION_END;
+    #endif // SERIAL_XON_XOFF
 
     #if ENABLED(EMERGENCY_PARSER)
       emergency_parser(c);
@@ -160,37 +250,41 @@
 
     FORCE_INLINE void _tx_udr_empty_irq(void) {
       // If interrupts are enabled, there must be more data in the output
-      // buffer. Send the next byte
-      const uint8_t t = tx_buffer.tail,
-                    c = tx_buffer.buffer[t];
-      tx_buffer.tail = (t + 1) & (TX_BUFFER_SIZE - 1);
-
-      M_UDRx = c;
+      // buffer.
+
+      #if ENABLED(SERIAL_XON_XOFF)
+        // Do a priority insertion of an XON/XOFF char, if needed.
+        const uint8_t state = xon_xoff_state;
+        if (!(state & XON_XOFF_CHAR_SENT)) {
+          M_UDRx = state & XON_XOFF_CHAR_MASK;
+          xon_xoff_state = state | XON_XOFF_CHAR_SENT;
+        }
+        else
+      #endif
+      { // Send the next byte
+        const uint8_t t = tx_buffer.tail, c = tx_buffer.buffer[t];
+        tx_buffer.tail = (t + 1) & (TX_BUFFER_SIZE - 1);
+        M_UDRx = c;
+      }
 
       // clear the TXC bit -- "can be cleared by writing a one to its bit
       // location". This makes sure flush() won't return until the bytes
       // actually got written
       SBI(M_UCSRxA, M_TXCx);
 
-      if (tx_buffer.head == tx_buffer.tail) {
-        // Buffer empty, so disable interrupts
+      // Disable interrupts if the buffer is empty
+      if (tx_buffer.head == tx_buffer.tail)
         CBI(M_UCSRxB, M_UDRIEx);
-      }
     }
 
     #ifdef M_USARTx_UDRE_vect
-      ISR(M_USARTx_UDRE_vect) {
-        _tx_udr_empty_irq();
-      }
+      ISR(M_USARTx_UDRE_vect) { _tx_udr_empty_irq(); }
     #endif
 
   #endif // TX_BUFFER_SIZE
 
   #ifdef M_USARTx_RX_vect
-    ISR(M_USARTx_RX_vect) {
-      const unsigned char c = M_UDRx;
-      store_char(c);
-    }
+    ISR(M_USARTx_RX_vect) { store_rxd_char(); }
   #endif
 
   // Public Methods
@@ -200,9 +294,9 @@
     bool useU2X = true;
 
     #if F_CPU == 16000000UL && SERIAL_PORT == 0
-      // hard-coded exception for compatibility with the bootloader shipped
-      // with the Duemilanove and previous boards and the firmware on the 8U2
-      // on the Uno and Mega 2560.
+      // Hard-coded exception for compatibility with the bootloader shipped
+      // with the Duemilanove and previous boards, and the firmware on the
+      // 8U2 on the Uno and Mega 2560.
       if (baud == 57600) useU2X = false;
     #endif
 
@@ -237,8 +331,9 @@
 
   void MarlinSerial::checkRx(void) {
     if (TEST(M_UCSRxA, M_RXCx)) {
-      const uint8_t c = M_UDRx;
-      store_char(c);
+      CRITICAL_SECTION_START;
+        store_rxd_char();
+      CRITICAL_SECTION_END;
     }
   }
 
@@ -252,47 +347,76 @@
   int MarlinSerial::read(void) {
     int v;
     CRITICAL_SECTION_START;
-      const uint8_t t = rx_buffer.tail;
+      const ring_buffer_pos_t t = rx_buffer.tail;
       if (rx_buffer.head == t)
         v = -1;
       else {
         v = rx_buffer.buffer[t];
-        rx_buffer.tail = (uint8_t)(t + 1) & (RX_BUFFER_SIZE - 1);
+        rx_buffer.tail = (ring_buffer_pos_t)(t + 1) & (RX_BUFFER_SIZE - 1);
+
+        #if ENABLED(SERIAL_XON_XOFF)
+          if ((xon_xoff_state & XON_XOFF_CHAR_MASK) == XOFF_CHAR) {
+            // Get count of bytes in the RX buffer
+            ring_buffer_pos_t rx_count = (ring_buffer_pos_t)(rx_buffer.head - rx_buffer.tail) & (ring_buffer_pos_t)(RX_BUFFER_SIZE - 1);
+            // When below 10% of RX buffer capacity, send XON before
+            // running out of RX buffer bytes
+            if (rx_count < (RX_BUFFER_SIZE) / 10) {
+              xon_xoff_state = XON_CHAR | XON_XOFF_CHAR_SENT;
+              CRITICAL_SECTION_END;       // End critical section before returning!
+              writeNoHandshake(XON_CHAR);
+              return v;
+            }
+          }
+        #endif
       }
     CRITICAL_SECTION_END;
     return v;
   }
 
-  uint8_t MarlinSerial::available(void) {
+  ring_buffer_pos_t MarlinSerial::available(void) {
     CRITICAL_SECTION_START;
-      const uint8_t h = rx_buffer.head,
-                    t = rx_buffer.tail;
+      const ring_buffer_pos_t h = rx_buffer.head, t = rx_buffer.tail;
     CRITICAL_SECTION_END;
-    return (uint8_t)(RX_BUFFER_SIZE + h - t) & (RX_BUFFER_SIZE - 1);
+    return (ring_buffer_pos_t)(RX_BUFFER_SIZE + h - t) & (RX_BUFFER_SIZE - 1);
   }
 
   void MarlinSerial::flush(void) {
-    // RX
-    // don't reverse this or there may be problems if the RX interrupt
-    // occurs after reading the value of rx_buffer_head but before writing
-    // the value to rx_buffer_tail; the previous value of rx_buffer_head
-    // may be written to rx_buffer_tail, making it appear as if the buffer
-    // were full, not empty.
+    // Don't change this order of operations. If the RX interrupt occurs between
+    // reading rx_buffer_head and updating rx_buffer_tail, the previous rx_buffer_head
+    // may be written to rx_buffer_tail, making the buffer appear full rather than empty.
     CRITICAL_SECTION_START;
       rx_buffer.head = rx_buffer.tail;
     CRITICAL_SECTION_END;
+
+    #if ENABLED(SERIAL_XON_XOFF)
+      if ((xon_xoff_state & XON_XOFF_CHAR_MASK) == XOFF_CHAR) {
+        xon_xoff_state = XON_CHAR | XON_XOFF_CHAR_SENT;
+        writeNoHandshake(XON_CHAR);
+      }
+    #endif
   }
 
   #if TX_BUFFER_SIZE > 0
     uint8_t MarlinSerial::availableForWrite(void) {
       CRITICAL_SECTION_START;
-        const uint8_t h = tx_buffer.head,
-                      t = tx_buffer.tail;
+        const uint8_t h = tx_buffer.head, t = tx_buffer.tail;
       CRITICAL_SECTION_END;
       return (uint8_t)(TX_BUFFER_SIZE + h - t) & (TX_BUFFER_SIZE - 1);
     }
 
     void MarlinSerial::write(const uint8_t c) {
+      #if ENABLED(SERIAL_XON_XOFF)
+        const uint8_t state = xon_xoff_state;
+        if (!(state & XON_XOFF_CHAR_SENT)) {
+          // Send 2 chars: XON/XOFF, then a user-specified char
+          writeNoHandshake(state & XON_XOFF_CHAR_MASK);
+          xon_xoff_state = state | XON_XOFF_CHAR_SENT;
+        }
+      #endif
+      writeNoHandshake(c);
+    }
+
+    void MarlinSerial::writeNoHandshake(const uint8_t c) {
       _written = true;
       CRITICAL_SECTION_START;
         bool emty = (tx_buffer.head == tx_buffer.tail);
@@ -353,20 +477,34 @@
       }
       // If we get here, nothing is queued anymore (DRIE is disabled) and
       // the hardware finished tranmission (TXC is set).
-  }
+    }
+
+  #else // TX_BUFFER_SIZE == 0
 
-  #else
-    void MarlinSerial::write(uint8_t c) {
-      while (!TEST(M_UCSRxA, M_UDREx))
-        ;
+    void MarlinSerial::write(const uint8_t c) {
+      while (!TEST(M_UCSRxA, M_UDREx)) { /* nada */ }
       M_UDRx = c;
+      #if ENABLED(SERIAL_XON_XOFF)
+        // Do a priority insertion of an XON/XOFF char, if needed.
+        const uint8_t state = xon_xoff_state;
+        if (!(state & XON_XOFF_CHAR_SENT)) {
+          writeNoHandshake(state & XON_XOFF_CHAR_MASK);
+          xon_xoff_state = state | XON_XOFF_CHAR_SENT;
+        }
+      #endif
+      writeNoHandshake(c);
     }
-  #endif
 
-  // end NEW
+    void MarlinSerial::writeNoHandshake(const uint8_t c) {
+      while (!TEST(M_UCSRxA, M_UDREx)) ;
+      M_UDRx = c;
+    }
 
-  /// imports from print.h
+  #endif // TX_BUFFER_SIZE == 0
 
+  /**
+   * Imports from print.h
+   */
 
   void MarlinSerial::print(char c, int base) {
     print((long)c, base);
@@ -516,4 +654,4 @@
   HardwareSerial bluetoothSerial;
 #endif
 
-#endif
+#endif // __AVR__
diff --git a/Marlin/src/HAL/HAL_AVR/MarlinSerial.h b/Marlin/src/HAL/HAL_AVR/MarlinSerial.h
index 0448e5502cb6828a43f3f5848755884d88e93d09..ef4f165e0c2515d7f94cb582509c0debd7cd42b6 100644
--- a/Marlin/src/HAL/HAL_AVR/MarlinSerial.h
+++ b/Marlin/src/HAL/HAL_AVR/MarlinSerial.h
@@ -21,13 +21,13 @@
  */
 
 /**
-  MarlinSerial.h - Hardware serial library for Wiring
-  Copyright (c) 2006 Nicholas Zambetti.  All right reserved.
-
-  Modified 28 September 2010 by Mark Sproul
-  Modified 14 February 2016 by Andreas Hardtung (added tx buffer)
-
-*/
+ * MarlinSerial.h - Hardware serial library for Wiring
+ * Copyright (c) 2006 Nicholas Zambetti.  All right reserved.
+ *
+ * Modified 28 September 2010 by Mark Sproul
+ * Modified 14 February 2016 by Andreas Hardtung (added tx buffer)
+ * Modified 01 October 2017 by Eduardo José Tagle (added XON/XOFF)
+ */
 
 #ifndef MARLINSERIAL_H
 #define MARLINSERIAL_H
@@ -89,34 +89,33 @@
   #ifndef TX_BUFFER_SIZE
     #define TX_BUFFER_SIZE 32
   #endif
-  #if !((RX_BUFFER_SIZE == 256) ||(RX_BUFFER_SIZE == 128) ||(RX_BUFFER_SIZE == 64) ||(RX_BUFFER_SIZE == 32) ||(RX_BUFFER_SIZE == 16) ||(RX_BUFFER_SIZE == 8) ||(RX_BUFFER_SIZE == 4) ||(RX_BUFFER_SIZE == 2))
-    #error "RX_BUFFER_SIZE has to be a power of 2 and >= 2"
-  #endif
-  #if !((TX_BUFFER_SIZE == 256) ||(TX_BUFFER_SIZE == 128) ||(TX_BUFFER_SIZE == 64) ||(TX_BUFFER_SIZE == 32) ||(TX_BUFFER_SIZE == 16) ||(TX_BUFFER_SIZE == 8) ||(TX_BUFFER_SIZE == 4) ||(TX_BUFFER_SIZE == 2) ||(TX_BUFFER_SIZE == 0))
-    #error TX_BUFFER_SIZE has to be a power of 2 or 0
+
+  #if ENABLED(SERIAL_XON_XOFF) && RX_BUFFER_SIZE < 1024
+    #error "XON/XOFF requires RX_BUFFER_SIZE >= 1024 for reliable transfers without drops."
   #endif
 
-  struct ring_buffer_r {
-    unsigned char buffer[RX_BUFFER_SIZE];
-    volatile uint8_t head;
-    volatile uint8_t tail;
-  };
+  #if !IS_POWER_OF_2(RX_BUFFER_SIZE) || RX_BUFFER_SIZE < 2
+    #error "RX_BUFFER_SIZE must be a power of 2 greater than 1."
+  #endif
 
-  #if TX_BUFFER_SIZE > 0
-    struct ring_buffer_t {
-      unsigned char buffer[TX_BUFFER_SIZE];
-      volatile uint8_t head;
-      volatile uint8_t tail;
-    };
+  #if TX_BUFFER_SIZE && (TX_BUFFER_SIZE < 2 || TX_BUFFER_SIZE > 256 || !IS_POWER_OF_2(TX_BUFFER_SIZE))
+    #error "TX_BUFFER_SIZE must be 0 or a power of 2 greater than 1."
   #endif
 
-  #if UART_PRESENT(SERIAL_PORT)
-    extern ring_buffer_r rx_buffer;
-    #if TX_BUFFER_SIZE > 0
-      extern ring_buffer_t tx_buffer;
-    #endif
+  #if RX_BUFFER_SIZE > 256
+    typedef uint16_t ring_buffer_pos_t;
+  #else
+    typedef uint8_t ring_buffer_pos_t;
+  #endif
+  
+  #if ENABLED(SERIAL_STATS_DROPPED_RX)
+    extern uint8_t rx_dropped_bytes;
   #endif
 
+  #if ENABLED(SERIAL_STATS_MAX_RX_QUEUED)
+    extern ring_buffer_pos_t rx_max_enqueued;
+  #endif  
+  
   class MarlinSerial { //: public Stream
 
     public:
@@ -126,19 +125,23 @@
       static int peek(void);
       static int read(void);
       static void flush(void);
-      static uint8_t available(void);
+      static ring_buffer_pos_t available(void);
       static void checkRx(void);
       static void write(const uint8_t c);
       #if TX_BUFFER_SIZE > 0
         static uint8_t availableForWrite(void);
         static void flushTX(void);
       #endif
+      static void writeNoHandshake(const uint8_t c);
 
-    private:
-      static void printNumber(unsigned long, const uint8_t);
-      static void printFloat(double, uint8_t);
+      #if ENABLED(SERIAL_STATS_DROPPED_RX)
+        FORCE_INLINE static uint32_t dropped() { return rx_dropped_bytes; }
+      #endif
+
+      #if ENABLED(SERIAL_STATS_MAX_RX_QUEUED)
+        FORCE_INLINE static ring_buffer_pos_t rxMaxEnqueued() { return rx_max_enqueued; }
+      #endif  
 
-    public:
       static FORCE_INLINE void write(const char* str) { while (*str) write(*str++); }
       static FORCE_INLINE void write(const uint8_t* buffer, size_t size) { while (size--) write(*buffer++); }
       static FORCE_INLINE void print(const String& s) { for (int i = 0; i < (int)s.length(); i++) write(s[i]); }
@@ -163,6 +166,10 @@
       static void println(double, int = 2);
       static void println(void);
       operator bool() { return true; }
+
+    private:
+      static void printNumber(unsigned long, const uint8_t);
+      static void printFloat(double, uint8_t);
   };
 
   extern MarlinSerial customizedSerial;
diff --git a/Marlin/src/config/default/Configuration.h b/Marlin/src/config/default/Configuration.h
index 526d01f7d60197479f91b584e4d78b55b6c07716..a43d2a0a0a3e9a2bea3fe2192eff04449d41c2da 100644
--- a/Marlin/src/config/default/Configuration.h
+++ b/Marlin/src/config/default/Configuration.h
@@ -108,8 +108,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 250000
 
diff --git a/Marlin/src/config/default/Configuration_adv.h b/Marlin/src/config/default/Configuration_adv.h
index fbab9b819118cf95e0eaea9c9386a8f3d33acb13..402c5b18cfb7d9ab50f6f857e1e5bfb265a1c2a4 100644
--- a/Marlin/src/config/default/Configuration_adv.h
+++ b/Marlin/src/config/default/Configuration_adv.h
@@ -751,7 +751,7 @@
 #define MAX_CMD_SIZE 96
 #define BUFSIZE 4
 
-// Transfer Buffer Size
+// Transmission to Host Buffer Size
 // To save 386 bytes of PROGMEM (and TX_BUFFER_SIZE+3 bytes of RAM) set to 0.
 // To buffer a simple "ok" you need 4 bytes.
 // For ADVANCED_OK (M105) you need 32 bytes.
@@ -760,6 +760,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 0
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410
diff --git a/Marlin/src/config/examples/AlephObjects/TAZ4/Configuration.h b/Marlin/src/config/examples/AlephObjects/TAZ4/Configuration.h
index 473e79221d3bbd62c8f3711205847da9ae76c312..0be730e33f708097b7626cec808ff4aecec1c65a 100644
--- a/Marlin/src/config/examples/AlephObjects/TAZ4/Configuration.h
+++ b/Marlin/src/config/examples/AlephObjects/TAZ4/Configuration.h
@@ -108,8 +108,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 250000
 
diff --git a/Marlin/src/config/examples/AlephObjects/TAZ4/Configuration_adv.h b/Marlin/src/config/examples/AlephObjects/TAZ4/Configuration_adv.h
index af3f5498da7aa770e67ca05555b58786cf45daf2..a87e55d9d7bdcb76869771330a32ada8d54cbde1 100644
--- a/Marlin/src/config/examples/AlephObjects/TAZ4/Configuration_adv.h
+++ b/Marlin/src/config/examples/AlephObjects/TAZ4/Configuration_adv.h
@@ -751,7 +751,7 @@
 #define MAX_CMD_SIZE 96
 #define BUFSIZE 4
 
-// Transfer Buffer Size
+// Transmission to Host Buffer Size
 // To save 386 bytes of PROGMEM (and TX_BUFFER_SIZE+3 bytes of RAM) set to 0.
 // To buffer a simple "ok" you need 4 bytes.
 // For ADVANCED_OK (M105) you need 32 bytes.
@@ -760,6 +760,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 0
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410
diff --git a/Marlin/src/config/examples/AliExpress/CL-260/Configuration.h b/Marlin/src/config/examples/AliExpress/CL-260/Configuration.h
index 0d51160b355508bbe0cf926abd187d303448df75..8d0b8f622c8826c823666b9bb24d14a4c3d53718 100644
--- a/Marlin/src/config/examples/AliExpress/CL-260/Configuration.h
+++ b/Marlin/src/config/examples/AliExpress/CL-260/Configuration.h
@@ -108,8 +108,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 250000
 
diff --git a/Marlin/src/config/examples/Anet/A6/Configuration.h b/Marlin/src/config/examples/Anet/A6/Configuration.h
index e0b0edc45b66f13bea16db16be5a095beb653c84..7e9e4b1bee7000cbbef33ed8eb4425e98d0c4ee6 100644
--- a/Marlin/src/config/examples/Anet/A6/Configuration.h
+++ b/Marlin/src/config/examples/Anet/A6/Configuration.h
@@ -108,8 +108,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 115200
 
diff --git a/Marlin/src/config/examples/Anet/A6/Configuration_adv.h b/Marlin/src/config/examples/Anet/A6/Configuration_adv.h
index ede7377a17ea21198e112ba8fd667bbcbf1dc236..26f0cecf15dab7e85fe728bec5e87c2a26014333 100644
--- a/Marlin/src/config/examples/Anet/A6/Configuration_adv.h
+++ b/Marlin/src/config/examples/Anet/A6/Configuration_adv.h
@@ -751,7 +751,7 @@
 #define MAX_CMD_SIZE 96
 #define BUFSIZE 4
 
-// Transfer Buffer Size
+// Transmission to Host Buffer Size
 // To save 386 bytes of PROGMEM (and TX_BUFFER_SIZE+3 bytes of RAM) set to 0.
 // To buffer a simple "ok" you need 4 bytes.
 // For ADVANCED_OK (M105) you need 32 bytes.
@@ -760,6 +760,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 0
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410
diff --git a/Marlin/src/config/examples/Anet/A8/Configuration.h b/Marlin/src/config/examples/Anet/A8/Configuration.h
index 15f4297e7bdd6742584f337fb8610886a461f0d8..53088a3ed69256e02c3057bc203d019bbce7819f 100644
--- a/Marlin/src/config/examples/Anet/A8/Configuration.h
+++ b/Marlin/src/config/examples/Anet/A8/Configuration.h
@@ -108,8 +108,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 115200
 
diff --git a/Marlin/src/config/examples/Anet/A8/Configuration_adv.h b/Marlin/src/config/examples/Anet/A8/Configuration_adv.h
index bfabeddd8bf910688b9a20f9cb436f981a9a8c46..195c520745e9f117fe6e15a7de603ae21bee8afd 100644
--- a/Marlin/src/config/examples/Anet/A8/Configuration_adv.h
+++ b/Marlin/src/config/examples/Anet/A8/Configuration_adv.h
@@ -751,7 +751,7 @@
 #define MAX_CMD_SIZE 96
 #define BUFSIZE 4
 
-// Transfer Buffer Size
+// Transmission to Host Buffer Size
 // To save 386 bytes of PROGMEM (and TX_BUFFER_SIZE+3 bytes of RAM) set to 0.
 // To buffer a simple "ok" you need 4 bytes.
 // For ADVANCED_OK (M105) you need 32 bytes.
@@ -760,6 +760,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 0
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410
diff --git a/Marlin/src/config/examples/BQ/Hephestos/Configuration.h b/Marlin/src/config/examples/BQ/Hephestos/Configuration.h
index c2869942777370f30a062aa8926f9e361540242c..0db288ec56a280d693709a7247a41a1cef3105cb 100644
--- a/Marlin/src/config/examples/BQ/Hephestos/Configuration.h
+++ b/Marlin/src/config/examples/BQ/Hephestos/Configuration.h
@@ -108,8 +108,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 115200
 
diff --git a/Marlin/src/config/examples/BQ/Hephestos/Configuration_adv.h b/Marlin/src/config/examples/BQ/Hephestos/Configuration_adv.h
index b923555d3681b64834d485c8df49ad35528a354e..14959bbfb2fb116d5bb2263d141ca8288713769f 100644
--- a/Marlin/src/config/examples/BQ/Hephestos/Configuration_adv.h
+++ b/Marlin/src/config/examples/BQ/Hephestos/Configuration_adv.h
@@ -751,7 +751,7 @@
 #define MAX_CMD_SIZE 96
 #define BUFSIZE 4
 
-// Transfer Buffer Size
+// Transmission to Host Buffer Size
 // To save 386 bytes of PROGMEM (and TX_BUFFER_SIZE+3 bytes of RAM) set to 0.
 // To buffer a simple "ok" you need 4 bytes.
 // For ADVANCED_OK (M105) you need 32 bytes.
@@ -760,6 +760,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 0
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410
diff --git a/Marlin/src/config/examples/BQ/Hephestos_2/Configuration.h b/Marlin/src/config/examples/BQ/Hephestos_2/Configuration.h
index 48196e464b0e98346da828dece94fc826c0e5e38..5f07e117e36a58db9f8c29206d69973ad15148f5 100644
--- a/Marlin/src/config/examples/BQ/Hephestos_2/Configuration.h
+++ b/Marlin/src/config/examples/BQ/Hephestos_2/Configuration.h
@@ -107,8 +107,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 115200
 
diff --git a/Marlin/src/config/examples/BQ/Hephestos_2/Configuration_adv.h b/Marlin/src/config/examples/BQ/Hephestos_2/Configuration_adv.h
index 96f241d7875d271d70ab899c4d65a77ac2b48b5f..82f0175d2625cec81ac0166d42d3a91815e68aa3 100644
--- a/Marlin/src/config/examples/BQ/Hephestos_2/Configuration_adv.h
+++ b/Marlin/src/config/examples/BQ/Hephestos_2/Configuration_adv.h
@@ -751,7 +751,7 @@
 #define MAX_CMD_SIZE 96
 #define BUFSIZE 4
 
-// Transfer Buffer Size
+// Transmission to Host Buffer Size
 // To save 386 bytes of PROGMEM (and TX_BUFFER_SIZE+3 bytes of RAM) set to 0.
 // To buffer a simple "ok" you need 4 bytes.
 // For ADVANCED_OK (M105) you need 32 bytes.
@@ -760,6 +760,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 32
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410
diff --git a/Marlin/src/config/examples/BQ/WITBOX/Configuration.h b/Marlin/src/config/examples/BQ/WITBOX/Configuration.h
index b3a5c24f94b21530b7f933de66dc8c93ed3acf0b..7b853cf2d9f485e638b8063edec61e9715af75a4 100644
--- a/Marlin/src/config/examples/BQ/WITBOX/Configuration.h
+++ b/Marlin/src/config/examples/BQ/WITBOX/Configuration.h
@@ -108,8 +108,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 115200
 
diff --git a/Marlin/src/config/examples/BQ/WITBOX/Configuration_adv.h b/Marlin/src/config/examples/BQ/WITBOX/Configuration_adv.h
index b923555d3681b64834d485c8df49ad35528a354e..14959bbfb2fb116d5bb2263d141ca8288713769f 100644
--- a/Marlin/src/config/examples/BQ/WITBOX/Configuration_adv.h
+++ b/Marlin/src/config/examples/BQ/WITBOX/Configuration_adv.h
@@ -751,7 +751,7 @@
 #define MAX_CMD_SIZE 96
 #define BUFSIZE 4
 
-// Transfer Buffer Size
+// Transmission to Host Buffer Size
 // To save 386 bytes of PROGMEM (and TX_BUFFER_SIZE+3 bytes of RAM) set to 0.
 // To buffer a simple "ok" you need 4 bytes.
 // For ADVANCED_OK (M105) you need 32 bytes.
@@ -760,6 +760,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 0
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410
diff --git a/Marlin/src/config/examples/Cartesio/Configuration.h b/Marlin/src/config/examples/Cartesio/Configuration.h
index af096eeaad1570011e091b021f0902d0e0d61f5c..b9b3dda1501798a189d0e2ab42ec7195832d91d1 100644
--- a/Marlin/src/config/examples/Cartesio/Configuration.h
+++ b/Marlin/src/config/examples/Cartesio/Configuration.h
@@ -108,8 +108,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 115200
 
diff --git a/Marlin/src/config/examples/Cartesio/Configuration_adv.h b/Marlin/src/config/examples/Cartesio/Configuration_adv.h
index 89253893cb5e5bca2dd706d74c486ff44a9e4b0c..f3a226fadf62ced9708d67058675382d7d799033 100644
--- a/Marlin/src/config/examples/Cartesio/Configuration_adv.h
+++ b/Marlin/src/config/examples/Cartesio/Configuration_adv.h
@@ -751,7 +751,7 @@
 #define MAX_CMD_SIZE 96
 #define BUFSIZE 4
 
-// Transfer Buffer Size
+// Transmission to Host Buffer Size
 // To save 386 bytes of PROGMEM (and TX_BUFFER_SIZE+3 bytes of RAM) set to 0.
 // To buffer a simple "ok" you need 4 bytes.
 // For ADVANCED_OK (M105) you need 32 bytes.
@@ -760,6 +760,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 0
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410
diff --git a/Marlin/src/config/examples/Creality/CR-10/Configuration.h b/Marlin/src/config/examples/Creality/CR-10/Configuration.h
index ab832f5aaa99b748cb450c5f98f39ed710c787ea..54c56eda7265362f52fdaf9d632c0c9a46c1da1a 100644
--- a/Marlin/src/config/examples/Creality/CR-10/Configuration.h
+++ b/Marlin/src/config/examples/Creality/CR-10/Configuration.h
@@ -108,8 +108,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 115200
 
diff --git a/Marlin/src/config/examples/Creality/CR-10/Configuration_adv.h b/Marlin/src/config/examples/Creality/CR-10/Configuration_adv.h
index c54556093fb9cc7a72be31c6976930475e877b98..4294fbdf9720404e3c22d597ca5ebdd37f7fd507 100644
--- a/Marlin/src/config/examples/Creality/CR-10/Configuration_adv.h
+++ b/Marlin/src/config/examples/Creality/CR-10/Configuration_adv.h
@@ -744,7 +744,7 @@
 #define MAX_CMD_SIZE 96
 #define BUFSIZE 4
 
-// Transfer Buffer Size
+// Transmission to Host Buffer Size
 // To save 386 bytes of PROGMEM (and TX_BUFFER_SIZE+3 bytes of RAM) set to 0.
 // To buffer a simple "ok" you need 4 bytes.
 // For ADVANCED_OK (M105) you need 32 bytes.
@@ -753,6 +753,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 0
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410
diff --git a/Marlin/src/config/examples/Felix/Configuration.h b/Marlin/src/config/examples/Felix/Configuration.h
index 15e9199f18f9a04f9e741199b2e0d0c0c199e913..940543c6c5a5cbdf3622ee138f1065b54aeb57ca 100644
--- a/Marlin/src/config/examples/Felix/Configuration.h
+++ b/Marlin/src/config/examples/Felix/Configuration.h
@@ -108,8 +108,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 250000
 
diff --git a/Marlin/src/config/examples/Felix/Configuration_adv.h b/Marlin/src/config/examples/Felix/Configuration_adv.h
index 03388ec5e6f6de4dd4160d3e4aaa5f5ba555aa19..e6e8d741f3b4ee24c2be8f9d20975a4506bd5934 100644
--- a/Marlin/src/config/examples/Felix/Configuration_adv.h
+++ b/Marlin/src/config/examples/Felix/Configuration_adv.h
@@ -751,7 +751,7 @@
 #define MAX_CMD_SIZE 96
 #define BUFSIZE 4
 
-// Transfer Buffer Size
+// Transmission to Host Buffer Size
 // To save 386 bytes of PROGMEM (and TX_BUFFER_SIZE+3 bytes of RAM) set to 0.
 // To buffer a simple "ok" you need 4 bytes.
 // For ADVANCED_OK (M105) you need 32 bytes.
@@ -760,6 +760,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 0
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410
diff --git a/Marlin/src/config/examples/Felix/DUAL/Configuration.h b/Marlin/src/config/examples/Felix/DUAL/Configuration.h
index 03317d455f65fe132346f6eb1e918a856d005d6a..9205c4e020e73f481dcab306d88fd0f4dd6b7dcf 100644
--- a/Marlin/src/config/examples/Felix/DUAL/Configuration.h
+++ b/Marlin/src/config/examples/Felix/DUAL/Configuration.h
@@ -108,8 +108,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 250000
 
diff --git a/Marlin/src/config/examples/Folger Tech/i3-2020/Configuration.h b/Marlin/src/config/examples/Folger Tech/i3-2020/Configuration.h
index e32b6defe067cd124422172e38959b7520b08b7f..1cd587b0c1ebd61c1def9872636ed3c21b839023 100644
--- a/Marlin/src/config/examples/Folger Tech/i3-2020/Configuration.h	
+++ b/Marlin/src/config/examples/Folger Tech/i3-2020/Configuration.h	
@@ -108,8 +108,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 250000
 
diff --git a/Marlin/src/config/examples/Folger Tech/i3-2020/Configuration_adv.h b/Marlin/src/config/examples/Folger Tech/i3-2020/Configuration_adv.h
index 91756afeb585f6ae55c7485e19118929a1c5b1cf..8f1fc71eeeeeffb07b5ec3d7186990fbd441ee79 100644
--- a/Marlin/src/config/examples/Folger Tech/i3-2020/Configuration_adv.h	
+++ b/Marlin/src/config/examples/Folger Tech/i3-2020/Configuration_adv.h	
@@ -751,7 +751,7 @@
 #define MAX_CMD_SIZE 96
 #define BUFSIZE 4
 
-// Transfer Buffer Size
+// Transmission to Host Buffer Size
 // To save 386 bytes of PROGMEM (and TX_BUFFER_SIZE+3 bytes of RAM) set to 0.
 // To buffer a simple "ok" you need 4 bytes.
 // For ADVANCED_OK (M105) you need 32 bytes.
@@ -760,6 +760,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 0
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410
diff --git a/Marlin/src/config/examples/Geeetech/GT2560/Configuration.h b/Marlin/src/config/examples/Geeetech/GT2560/Configuration.h
index dcb66d3ccd60b560c2b6ad21aec7cdafadc5f213..37a8c30d611c33c152957b6c07071de4bfcaf3e4 100644
--- a/Marlin/src/config/examples/Geeetech/GT2560/Configuration.h
+++ b/Marlin/src/config/examples/Geeetech/GT2560/Configuration.h
@@ -108,8 +108,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 250000
 
diff --git a/Marlin/src/config/examples/Geeetech/I3_Pro_X-GT2560/Configuration.h b/Marlin/src/config/examples/Geeetech/I3_Pro_X-GT2560/Configuration.h
index 44faead84d0f1623103456607e77e8f7489adced..702ed68e4b53d582d9302ef033b4383d416be6dd 100644
--- a/Marlin/src/config/examples/Geeetech/I3_Pro_X-GT2560/Configuration.h
+++ b/Marlin/src/config/examples/Geeetech/I3_Pro_X-GT2560/Configuration.h
@@ -108,8 +108,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 250000
 
diff --git a/Marlin/src/config/examples/Infitary/i3-M508/Configuration.h b/Marlin/src/config/examples/Infitary/i3-M508/Configuration.h
index b3c9ef5079442176c26062923a4388e61617cd4a..61a3cd903ae02d526bd34a61e0cb466875f281fa 100644
--- a/Marlin/src/config/examples/Infitary/i3-M508/Configuration.h
+++ b/Marlin/src/config/examples/Infitary/i3-M508/Configuration.h
@@ -108,8 +108,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 250000
 
diff --git a/Marlin/src/config/examples/Infitary/i3-M508/Configuration_adv.h b/Marlin/src/config/examples/Infitary/i3-M508/Configuration_adv.h
index 8bc5dec84d00f0d598e3f5aa6ed9d0ea602d8907..f0d026ad19b0347a8f7f125a29f292a4ef8d8828 100644
--- a/Marlin/src/config/examples/Infitary/i3-M508/Configuration_adv.h
+++ b/Marlin/src/config/examples/Infitary/i3-M508/Configuration_adv.h
@@ -751,7 +751,7 @@
 #define MAX_CMD_SIZE 96
 #define BUFSIZE 4
 
-// Transfer Buffer Size
+// Transmission to Host Buffer Size
 // To save 386 bytes of PROGMEM (and TX_BUFFER_SIZE+3 bytes of RAM) set to 0.
 // To buffer a simple "ok" you need 4 bytes.
 // For ADVANCED_OK (M105) you need 32 bytes.
@@ -760,6 +760,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 0
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410
diff --git a/Marlin/src/config/examples/Malyan/M150/Configuration.h b/Marlin/src/config/examples/Malyan/M150/Configuration.h
index 5f4788b4c8bd1d87bd816a1e26df1adb8ac648ac..41bb37b518f32be11b62c90f35a2873575bc5420 100644
--- a/Marlin/src/config/examples/Malyan/M150/Configuration.h
+++ b/Marlin/src/config/examples/Malyan/M150/Configuration.h
@@ -113,8 +113,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 115200
 
diff --git a/Marlin/src/config/examples/Malyan/M150/Configuration_adv.h b/Marlin/src/config/examples/Malyan/M150/Configuration_adv.h
index 6e1b1dbdff8d518fe64f6d5a4e2eef4cff905840..7c53fc182d1c563b47b04814cb24aadb5174a83f 100644
--- a/Marlin/src/config/examples/Malyan/M150/Configuration_adv.h
+++ b/Marlin/src/config/examples/Malyan/M150/Configuration_adv.h
@@ -751,7 +751,7 @@
 #define MAX_CMD_SIZE 96
 #define BUFSIZE 4
 
-// Transfer Buffer Size
+// Transmission to Host Buffer Size
 // To save 386 bytes of PROGMEM (and TX_BUFFER_SIZE+3 bytes of RAM) set to 0.
 // To buffer a simple "ok" you need 4 bytes.
 // For ADVANCED_OK (M105) you need 32 bytes.
@@ -760,6 +760,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 0
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410
diff --git a/Marlin/src/config/examples/RepRapWorld/Megatronics/Configuration.h b/Marlin/src/config/examples/RepRapWorld/Megatronics/Configuration.h
index 54de5179858f2a9bb87f41dc0c2ff2d48e84f306..ec17af5a2c2388bdf513ea840192e6f841adbbb4 100644
--- a/Marlin/src/config/examples/RepRapWorld/Megatronics/Configuration.h
+++ b/Marlin/src/config/examples/RepRapWorld/Megatronics/Configuration.h
@@ -108,8 +108,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 250000
 
diff --git a/Marlin/src/config/examples/RigidBot/Configuration.h b/Marlin/src/config/examples/RigidBot/Configuration.h
index 28dd6a8349c91647bf4bb67e107d93ecb3d32684..ad4d2f9a7de5007c13bcd659014107e2a335225f 100644
--- a/Marlin/src/config/examples/RigidBot/Configuration.h
+++ b/Marlin/src/config/examples/RigidBot/Configuration.h
@@ -108,8 +108,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 115200
 
diff --git a/Marlin/src/config/examples/RigidBot/Configuration_adv.h b/Marlin/src/config/examples/RigidBot/Configuration_adv.h
index 3eaddb2647adb3146fc0dbf0583a45309bf9e4f4..f687e25ed03f76e20d287fa7c281cfbf0acbb091 100644
--- a/Marlin/src/config/examples/RigidBot/Configuration_adv.h
+++ b/Marlin/src/config/examples/RigidBot/Configuration_adv.h
@@ -751,7 +751,7 @@
 #define MAX_CMD_SIZE 96
 #define BUFSIZE 8
 
-// Transfer Buffer Size
+// Transmission to Host Buffer Size
 // To save 386 bytes of PROGMEM (and TX_BUFFER_SIZE+3 bytes of RAM) set to 0.
 // To buffer a simple "ok" you need 4 bytes.
 // For ADVANCED_OK (M105) you need 32 bytes.
@@ -760,6 +760,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 0
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410
diff --git a/Marlin/src/config/examples/SCARA/Configuration.h b/Marlin/src/config/examples/SCARA/Configuration.h
index 203d99b7114c077130dd2394e1de77a6e6687228..2a93c515239493a3153a4f18d90a89faa0760114 100644
--- a/Marlin/src/config/examples/SCARA/Configuration.h
+++ b/Marlin/src/config/examples/SCARA/Configuration.h
@@ -138,8 +138,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 250000
 
diff --git a/Marlin/src/config/examples/SCARA/Configuration_adv.h b/Marlin/src/config/examples/SCARA/Configuration_adv.h
index 040a72b833c45716c9b4f57e83d97a215c9727ac..42ffe17a68d2dc3f61e327753b5cf8bf1cc85e50 100644
--- a/Marlin/src/config/examples/SCARA/Configuration_adv.h
+++ b/Marlin/src/config/examples/SCARA/Configuration_adv.h
@@ -751,7 +751,7 @@
 #define MAX_CMD_SIZE 96
 #define BUFSIZE 4
 
-// Transfer Buffer Size
+// Transmission to Host Buffer Size
 // To save 386 bytes of PROGMEM (and TX_BUFFER_SIZE+3 bytes of RAM) set to 0.
 // To buffer a simple "ok" you need 4 bytes.
 // For ADVANCED_OK (M105) you need 32 bytes.
@@ -760,6 +760,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 0
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410
diff --git a/Marlin/src/config/examples/Sanguinololu/Configuration.h b/Marlin/src/config/examples/Sanguinololu/Configuration.h
index 970c8eee7d766e58cf87018bd3161ea06a16360c..897c70a432fa28367685e595a469becb3f6c5c68 100644
--- a/Marlin/src/config/examples/Sanguinololu/Configuration.h
+++ b/Marlin/src/config/examples/Sanguinololu/Configuration.h
@@ -108,8 +108,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 115200
 
diff --git a/Marlin/src/config/examples/Sanguinololu/Configuration_adv.h b/Marlin/src/config/examples/Sanguinololu/Configuration_adv.h
index 2b265c02cf65650e97a2ceaa43956730f0ad28c1..b8df16589b75400fb25cd62f0652aa72124245ab 100644
--- a/Marlin/src/config/examples/Sanguinololu/Configuration_adv.h
+++ b/Marlin/src/config/examples/Sanguinololu/Configuration_adv.h
@@ -740,7 +740,7 @@
 #define MAX_CMD_SIZE 96
 #define BUFSIZE 4
 
-// Transfer Buffer Size
+// Transmission to Host Buffer Size
 // To save 386 bytes of PROGMEM (and TX_BUFFER_SIZE+3 bytes of RAM) set to 0.
 // To buffer a simple "ok" you need 4 bytes.
 // For ADVANCED_OK (M105) you need 32 bytes.
@@ -749,6 +749,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 0
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410
diff --git a/Marlin/src/config/examples/TinyBoy2/Configuration.h b/Marlin/src/config/examples/TinyBoy2/Configuration.h
index 55ff8fddc8ad54308f8bdcddc9bb0625e678c657..e252f5c605ecb5df7fe974f02b1f645060e7f7b6 100644
--- a/Marlin/src/config/examples/TinyBoy2/Configuration.h
+++ b/Marlin/src/config/examples/TinyBoy2/Configuration.h
@@ -124,8 +124,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 115200
 
diff --git a/Marlin/src/config/examples/TinyBoy2/Configuration_adv.h b/Marlin/src/config/examples/TinyBoy2/Configuration_adv.h
index c4b98fcd16048e4060611c2adf919df7ae7847d2..85afa6ed924e04b7656850f1469c6c3a8109c290 100644
--- a/Marlin/src/config/examples/TinyBoy2/Configuration_adv.h
+++ b/Marlin/src/config/examples/TinyBoy2/Configuration_adv.h
@@ -751,7 +751,7 @@
 #define MAX_CMD_SIZE 96
 #define BUFSIZE 4
 
-// Transfer Buffer Size
+// Transmission to Host Buffer Size
 // To save 386 bytes of PROGMEM (and TX_BUFFER_SIZE+3 bytes of RAM) set to 0.
 // To buffer a simple "ok" you need 4 bytes.
 // For ADVANCED_OK (M105) you need 32 bytes.
@@ -760,6 +760,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 64
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410
diff --git a/Marlin/src/config/examples/Velleman/K8200/Configuration.h b/Marlin/src/config/examples/Velleman/K8200/Configuration.h
index 08968bf91e6d69ce52da6ad4a9dbfc1ee6e0e48f..94d0ccf9c974e631b32591db77a0a784b4e53e3f 100644
--- a/Marlin/src/config/examples/Velleman/K8200/Configuration.h
+++ b/Marlin/src/config/examples/Velleman/K8200/Configuration.h
@@ -124,8 +124,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 250000
 
diff --git a/Marlin/src/config/examples/Velleman/K8200/Configuration_adv.h b/Marlin/src/config/examples/Velleman/K8200/Configuration_adv.h
index b4b5125f7ce8c6791d641a546798739c46839c20..bc03354b34a0f36305ed51728060b22378271a83 100644
--- a/Marlin/src/config/examples/Velleman/K8200/Configuration_adv.h
+++ b/Marlin/src/config/examples/Velleman/K8200/Configuration_adv.h
@@ -764,7 +764,7 @@
 #define MAX_CMD_SIZE 96
 #define BUFSIZE 4
 
-// Transfer Buffer Size
+// Transmission to Host Buffer Size
 // To save 386 bytes of PROGMEM (and TX_BUFFER_SIZE+3 bytes of RAM) set to 0.
 // To buffer a simple "ok" you need 4 bytes.
 // For ADVANCED_OK (M105) you need 32 bytes.
@@ -773,6 +773,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 128
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410
diff --git a/Marlin/src/config/examples/Velleman/K8400/Configuration.h b/Marlin/src/config/examples/Velleman/K8400/Configuration.h
index be0030f039f9f5fedf138a142373b6a4d4b1b887..23fff324a4b773343f776f644be91a5ccf09938c 100644
--- a/Marlin/src/config/examples/Velleman/K8400/Configuration.h
+++ b/Marlin/src/config/examples/Velleman/K8400/Configuration.h
@@ -108,8 +108,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 250000
 
diff --git a/Marlin/src/config/examples/Velleman/K8400/Configuration_adv.h b/Marlin/src/config/examples/Velleman/K8400/Configuration_adv.h
index ba146b30fa4d0f564e5d69b893f68cc8d9caf2b2..0f46a008d400e9be698a01b6923f3cf0b6686c66 100644
--- a/Marlin/src/config/examples/Velleman/K8400/Configuration_adv.h
+++ b/Marlin/src/config/examples/Velleman/K8400/Configuration_adv.h
@@ -751,7 +751,7 @@
 #define MAX_CMD_SIZE 96
 #define BUFSIZE 26
 
-// Transfer Buffer Size
+// Transmission to Host Buffer Size
 // To save 386 bytes of PROGMEM (and TX_BUFFER_SIZE+3 bytes of RAM) set to 0.
 // To buffer a simple "ok" you need 4 bytes.
 // For ADVANCED_OK (M105) you need 32 bytes.
@@ -760,6 +760,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 0
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410
diff --git a/Marlin/src/config/examples/Velleman/K8400/Dual-head/Configuration.h b/Marlin/src/config/examples/Velleman/K8400/Dual-head/Configuration.h
index e40bcade8009838f811bf851e82ff0f1cd137b28..0d1099c79ae49c2808aee190247fcb27637e0124 100644
--- a/Marlin/src/config/examples/Velleman/K8400/Dual-head/Configuration.h
+++ b/Marlin/src/config/examples/Velleman/K8400/Dual-head/Configuration.h
@@ -108,8 +108,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 250000
 
diff --git a/Marlin/src/config/examples/adafruit/ST7565/Configuration.h b/Marlin/src/config/examples/adafruit/ST7565/Configuration.h
index 7ed947b62bec0ad1bcde5ecd6623eb29567c03a3..4371d684d39d4cf319a582d30b128b1505e5e1e3 100644
--- a/Marlin/src/config/examples/adafruit/ST7565/Configuration.h
+++ b/Marlin/src/config/examples/adafruit/ST7565/Configuration.h
@@ -108,8 +108,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 250000
 
diff --git a/Marlin/src/config/examples/delta/FLSUN/auto_calibrate/Configuration.h b/Marlin/src/config/examples/delta/FLSUN/auto_calibrate/Configuration.h
index e01ee072a170fece948f74d178deaacf180d9a30..8dd3b8aa30c86e831ad14028f0dab863a0d93e4e 100644
--- a/Marlin/src/config/examples/delta/FLSUN/auto_calibrate/Configuration.h
+++ b/Marlin/src/config/examples/delta/FLSUN/auto_calibrate/Configuration.h
@@ -108,8 +108,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 250000
 
diff --git a/Marlin/src/config/examples/delta/FLSUN/auto_calibrate/Configuration_adv.h b/Marlin/src/config/examples/delta/FLSUN/auto_calibrate/Configuration_adv.h
index 66084ad79de7dc41bdeab41068fc5a3d5e7c2863..0c837ada3f88d58c4c5c307ac71317920702c07e 100644
--- a/Marlin/src/config/examples/delta/FLSUN/auto_calibrate/Configuration_adv.h
+++ b/Marlin/src/config/examples/delta/FLSUN/auto_calibrate/Configuration_adv.h
@@ -753,7 +753,7 @@
 #define MAX_CMD_SIZE 96
 #define BUFSIZE 4
 
-// Transfer Buffer Size
+// Transmission to Host Buffer Size
 // To save 386 bytes of PROGMEM (and TX_BUFFER_SIZE+3 bytes of RAM) set to 0.
 // To buffer a simple "ok" you need 4 bytes.
 // For ADVANCED_OK (M105) you need 32 bytes.
@@ -762,6 +762,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 0
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410
diff --git a/Marlin/src/config/examples/delta/FLSUN/kossel_mini/Configuration.h b/Marlin/src/config/examples/delta/FLSUN/kossel_mini/Configuration.h
index aec87c8c1c5f08dc9a3cb7a0751b602a66841967..198dfea8edff2c24f1d68aa7112ee2264b7c4c1b 100644
--- a/Marlin/src/config/examples/delta/FLSUN/kossel_mini/Configuration.h
+++ b/Marlin/src/config/examples/delta/FLSUN/kossel_mini/Configuration.h
@@ -108,8 +108,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 250000
 
diff --git a/Marlin/src/config/examples/delta/FLSUN/kossel_mini/Configuration_adv.h b/Marlin/src/config/examples/delta/FLSUN/kossel_mini/Configuration_adv.h
index c8b8e6e9b546c91afd576215a981557192aaa053..88f8444eb2f071a8d6b0f47f861e1e26ee1251b9 100644
--- a/Marlin/src/config/examples/delta/FLSUN/kossel_mini/Configuration_adv.h
+++ b/Marlin/src/config/examples/delta/FLSUN/kossel_mini/Configuration_adv.h
@@ -753,7 +753,7 @@
 #define MAX_CMD_SIZE 96
 #define BUFSIZE 4
 
-// Transfer Buffer Size
+// Transmission to Host Buffer Size
 // To save 386 bytes of PROGMEM (and TX_BUFFER_SIZE+3 bytes of RAM) set to 0.
 // To buffer a simple "ok" you need 4 bytes.
 // For ADVANCED_OK (M105) you need 32 bytes.
@@ -762,6 +762,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 0
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410
diff --git a/Marlin/src/config/examples/delta/generic/Configuration.h b/Marlin/src/config/examples/delta/generic/Configuration.h
index 0dfe304e2986c25da268cfd03651b563019b8433..4257c49ba6ffc1b2ad0297fa5cc507a41b3ee69c 100644
--- a/Marlin/src/config/examples/delta/generic/Configuration.h
+++ b/Marlin/src/config/examples/delta/generic/Configuration.h
@@ -108,8 +108,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 250000
 
diff --git a/Marlin/src/config/examples/delta/generic/Configuration_adv.h b/Marlin/src/config/examples/delta/generic/Configuration_adv.h
index c8b8e6e9b546c91afd576215a981557192aaa053..88f8444eb2f071a8d6b0f47f861e1e26ee1251b9 100644
--- a/Marlin/src/config/examples/delta/generic/Configuration_adv.h
+++ b/Marlin/src/config/examples/delta/generic/Configuration_adv.h
@@ -753,7 +753,7 @@
 #define MAX_CMD_SIZE 96
 #define BUFSIZE 4
 
-// Transfer Buffer Size
+// Transmission to Host Buffer Size
 // To save 386 bytes of PROGMEM (and TX_BUFFER_SIZE+3 bytes of RAM) set to 0.
 // To buffer a simple "ok" you need 4 bytes.
 // For ADVANCED_OK (M105) you need 32 bytes.
@@ -762,6 +762,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 0
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410
diff --git a/Marlin/src/config/examples/delta/kossel_mini/Configuration.h b/Marlin/src/config/examples/delta/kossel_mini/Configuration.h
index e0f59056d072a26ccb1731745e09238dd0829a77..599c005183ed7fc2d736224dc3cfe025f1c42a1e 100644
--- a/Marlin/src/config/examples/delta/kossel_mini/Configuration.h
+++ b/Marlin/src/config/examples/delta/kossel_mini/Configuration.h
@@ -108,8 +108,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 250000
 
diff --git a/Marlin/src/config/examples/delta/kossel_mini/Configuration_adv.h b/Marlin/src/config/examples/delta/kossel_mini/Configuration_adv.h
index c8b8e6e9b546c91afd576215a981557192aaa053..88f8444eb2f071a8d6b0f47f861e1e26ee1251b9 100644
--- a/Marlin/src/config/examples/delta/kossel_mini/Configuration_adv.h
+++ b/Marlin/src/config/examples/delta/kossel_mini/Configuration_adv.h
@@ -753,7 +753,7 @@
 #define MAX_CMD_SIZE 96
 #define BUFSIZE 4
 
-// Transfer Buffer Size
+// Transmission to Host Buffer Size
 // To save 386 bytes of PROGMEM (and TX_BUFFER_SIZE+3 bytes of RAM) set to 0.
 // To buffer a simple "ok" you need 4 bytes.
 // For ADVANCED_OK (M105) you need 32 bytes.
@@ -762,6 +762,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 0
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410
diff --git a/Marlin/src/config/examples/delta/kossel_pro/Configuration.h b/Marlin/src/config/examples/delta/kossel_pro/Configuration.h
index 0b5fb3d2a7beb30ad4ebec9345ca7d4d25e408a9..9d2b846ee80b606e0fb6d991f13ee0bad661dda6 100644
--- a/Marlin/src/config/examples/delta/kossel_pro/Configuration.h
+++ b/Marlin/src/config/examples/delta/kossel_pro/Configuration.h
@@ -112,8 +112,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 115200
 
diff --git a/Marlin/src/config/examples/delta/kossel_pro/Configuration_adv.h b/Marlin/src/config/examples/delta/kossel_pro/Configuration_adv.h
index 872875b7e4a992eea087f32482d0d0382351112a..142d59ba61f09498140b27d91b3104cca4abfb27 100644
--- a/Marlin/src/config/examples/delta/kossel_pro/Configuration_adv.h
+++ b/Marlin/src/config/examples/delta/kossel_pro/Configuration_adv.h
@@ -758,7 +758,7 @@
 #define MAX_CMD_SIZE 96
 #define BUFSIZE 4
 
-// Transfer Buffer Size
+// Transmission to Host Buffer Size
 // To save 386 bytes of PROGMEM (and TX_BUFFER_SIZE+3 bytes of RAM) set to 0.
 // To buffer a simple "ok" you need 4 bytes.
 // For ADVANCED_OK (M105) you need 32 bytes.
@@ -767,6 +767,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 0
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410
diff --git a/Marlin/src/config/examples/delta/kossel_xl/Configuration.h b/Marlin/src/config/examples/delta/kossel_xl/Configuration.h
index 759067f7cb975b76abb37ebfceaf68146b34a77f..e47040182f75174859b3ee2fc971e086eb365453 100644
--- a/Marlin/src/config/examples/delta/kossel_xl/Configuration.h
+++ b/Marlin/src/config/examples/delta/kossel_xl/Configuration.h
@@ -108,8 +108,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 250000
 
diff --git a/Marlin/src/config/examples/delta/kossel_xl/Configuration_adv.h b/Marlin/src/config/examples/delta/kossel_xl/Configuration_adv.h
index 750f06e86b9a6ddf718d11d24f15e81083936cff..8b7c98341ea1b5866e249a8a3937b1bd2bcb6004 100644
--- a/Marlin/src/config/examples/delta/kossel_xl/Configuration_adv.h
+++ b/Marlin/src/config/examples/delta/kossel_xl/Configuration_adv.h
@@ -753,7 +753,7 @@
 #define MAX_CMD_SIZE 96
 #define BUFSIZE 4
 
-// Transfer Buffer Size
+// Transmission to Host Buffer Size
 // To save 386 bytes of PROGMEM (and TX_BUFFER_SIZE+3 bytes of RAM) set to 0.
 // To buffer a simple "ok" you need 4 bytes.
 // For ADVANCED_OK (M105) you need 32 bytes.
@@ -762,6 +762,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 0
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410
diff --git a/Marlin/src/config/examples/gCreate/gMax1.5+/Configuration.h b/Marlin/src/config/examples/gCreate/gMax1.5+/Configuration.h
index 8fecea505fcb4a0a70231c946c88fe6b7cf31376..4130c1c82d2c682a983d60ff049825eb65ff2038 100644
--- a/Marlin/src/config/examples/gCreate/gMax1.5+/Configuration.h
+++ b/Marlin/src/config/examples/gCreate/gMax1.5+/Configuration.h
@@ -108,8 +108,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 250000
 
diff --git a/Marlin/src/config/examples/gCreate/gMax1.5+/Configuration_adv.h b/Marlin/src/config/examples/gCreate/gMax1.5+/Configuration_adv.h
index 6b6bde353cfc5aec03aca760837c933cfe81bac5..7990eb38129b170d810ceca92224e0f9530cd5ac 100644
--- a/Marlin/src/config/examples/gCreate/gMax1.5+/Configuration_adv.h
+++ b/Marlin/src/config/examples/gCreate/gMax1.5+/Configuration_adv.h
@@ -751,7 +751,7 @@
 #define MAX_CMD_SIZE 96
 #define BUFSIZE 4
 
-// Transfer Buffer Size
+// Transmission to Host Buffer Size
 // To save 386 bytes of PROGMEM (and TX_BUFFER_SIZE+3 bytes of RAM) set to 0.
 // To buffer a simple "ok" you need 4 bytes.
 // For ADVANCED_OK (M105) you need 32 bytes.
@@ -760,6 +760,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 32
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410
diff --git a/Marlin/src/config/examples/makibox/Configuration.h b/Marlin/src/config/examples/makibox/Configuration.h
index 08fea9160d10f439c2f9f78746a2fb7f38243d39..7fb4b0be141f5c0713154af4e53ce84567db4439 100644
--- a/Marlin/src/config/examples/makibox/Configuration.h
+++ b/Marlin/src/config/examples/makibox/Configuration.h
@@ -108,8 +108,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 250000
 
diff --git a/Marlin/src/config/examples/makibox/Configuration_adv.h b/Marlin/src/config/examples/makibox/Configuration_adv.h
index 5bc751058362448d62056fe940cc61743383adff..ca090dda47daca1200b796dc4b458d4680dd38f4 100644
--- a/Marlin/src/config/examples/makibox/Configuration_adv.h
+++ b/Marlin/src/config/examples/makibox/Configuration_adv.h
@@ -751,7 +751,7 @@
 #define MAX_CMD_SIZE 96
 #define BUFSIZE 4
 
-// Transfer Buffer Size
+// Transmission to Host Buffer Size
 // To save 386 bytes of PROGMEM (and TX_BUFFER_SIZE+3 bytes of RAM) set to 0.
 // To buffer a simple "ok" you need 4 bytes.
 // For ADVANCED_OK (M105) you need 32 bytes.
@@ -760,6 +760,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 0
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410
diff --git a/Marlin/src/config/examples/stm32f103ret6/Configuration.h b/Marlin/src/config/examples/stm32f103ret6/Configuration.h
index 0d0b0ce1becaf291d5775046d55d3fe163452f25..434fd25b1a923eb17440585338942f8ed0712d04 100644
--- a/Marlin/src/config/examples/stm32f103ret6/Configuration.h
+++ b/Marlin/src/config/examples/stm32f103ret6/Configuration.h
@@ -107,8 +107,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 250000
 
diff --git a/Marlin/src/config/examples/tvrrug/Round2/Configuration.h b/Marlin/src/config/examples/tvrrug/Round2/Configuration.h
index 1f0cd8fff1cc20976cff8620f14a4a54863a6870..4e6a260d764c96402e920f6954c315611b1a42dc 100644
--- a/Marlin/src/config/examples/tvrrug/Round2/Configuration.h
+++ b/Marlin/src/config/examples/tvrrug/Round2/Configuration.h
@@ -108,8 +108,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 250000
 
diff --git a/Marlin/src/config/examples/tvrrug/Round2/Configuration_adv.h b/Marlin/src/config/examples/tvrrug/Round2/Configuration_adv.h
index 3102decf02036b861d92fb0016d406e6995da33a..853fc544548279adad4fa4c87b513c2005a45e82 100644
--- a/Marlin/src/config/examples/tvrrug/Round2/Configuration_adv.h
+++ b/Marlin/src/config/examples/tvrrug/Round2/Configuration_adv.h
@@ -751,7 +751,7 @@
 #define MAX_CMD_SIZE 96
 #define BUFSIZE 4
 
-// Transfer Buffer Size
+// Transmission to Host Buffer Size
 // To save 386 bytes of PROGMEM (and TX_BUFFER_SIZE+3 bytes of RAM) set to 0.
 // To buffer a simple "ok" you need 4 bytes.
 // For ADVANCED_OK (M105) you need 32 bytes.
@@ -760,6 +760,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 0
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410
diff --git a/Marlin/src/config/examples/wt150/Configuration.h b/Marlin/src/config/examples/wt150/Configuration.h
index e185358b2a2a5625d0d30b23048f995e20327f0d..b9a858205a668117a1031f893768bb805be44ea2 100644
--- a/Marlin/src/config/examples/wt150/Configuration.h
+++ b/Marlin/src/config/examples/wt150/Configuration.h
@@ -108,8 +108,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 115200
 
diff --git a/Marlin/src/config/examples/wt150/Configuration_adv.h b/Marlin/src/config/examples/wt150/Configuration_adv.h
index 0d472ff691e1cf9c391680da99df8215c190ae20..8d1ee372c52a58c129d02290542e24cd9c321825 100644
--- a/Marlin/src/config/examples/wt150/Configuration_adv.h
+++ b/Marlin/src/config/examples/wt150/Configuration_adv.h
@@ -751,7 +751,7 @@
 #define MAX_CMD_SIZE 96
 #define BUFSIZE 4
 
-// Transfer Buffer Size
+// Transmission to Host Buffer Size
 // To save 386 bytes of PROGMEM (and TX_BUFFER_SIZE+3 bytes of RAM) set to 0.
 // To buffer a simple "ok" you need 4 bytes.
 // For ADVANCED_OK (M105) you need 32 bytes.
@@ -760,6 +760,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 0
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410
diff --git a/Marlin/src/core/macros.h b/Marlin/src/core/macros.h
index e2f25eed4b58b1b0a5bfddf60db057c3f28e80b3..a89b6dafcead6554cdab8a9eea00db8cfb4cf7f8 100644
--- a/Marlin/src/core/macros.h
+++ b/Marlin/src/core/macros.h
@@ -106,6 +106,7 @@
 #define CIRCLE_CIRC(R) (2.0 * M_PI * (R))
 
 #define SIGN(a) ((a>0)-(a<0))
+#define IS_POWER_OF_2(x) ((x) && !((x) & ((x) - 1)))
 
 // Macros to contrain values
 #define NOLESS(v,n) do{ if (v < n) v = n; }while(0)
diff --git a/Marlin/src/gcode/queue.cpp b/Marlin/src/gcode/queue.cpp
index 09c49933a62dc2d89c2dd859afb3d7e58a739c36..fd28d20cfee1035d4cd637aacd8e675e9977de6a 100644
--- a/Marlin/src/gcode/queue.cpp
+++ b/Marlin/src/gcode/queue.cpp
@@ -221,9 +221,9 @@ inline void get_serial_commands() {
   /**
    * Loop while serial characters are incoming and the queue is not full
    */
-  while (commands_in_queue < BUFSIZE && MYSERIAL.available() > 0) {
-
-    char serial_char = MYSERIAL.read();
+  int c;
+  while (commands_in_queue < BUFSIZE && (c = MYSERIAL.read()) >= 0) {
+    char serial_char = c;
 
     /**
      * If the character ends the line
@@ -323,12 +323,9 @@ inline void get_serial_commands() {
       // The command will be injected when EOL is reached
     }
     else if (serial_char == '\\') {  // Handle escapes
-      if (MYSERIAL.available() > 0) {
-        // if we have one more character, copy it over
-        serial_char = MYSERIAL.read();
-        if (!serial_comment_mode) serial_line_buffer[serial_count++] = serial_char;
-      }
-      // otherwise do nothing
+      // if we have one more character, copy it over
+      if ((c = MYSERIAL.read()) >= 0 && !serial_comment_mode)
+        serial_line_buffer[serial_count++] = serial_char;
     }
     else { // it's not a newline, carriage return or escape char
       if (serial_char == ';') serial_comment_mode = true;
@@ -448,6 +445,15 @@ void advance_command_queue() {
         // M29 closes the file
         card.closefile();
         SERIAL_PROTOCOLLNPGM(MSG_FILE_SAVED);
+
+        #if ENABLED(SERIAL_STATS_DROPPED_RX)
+          SERIAL_ECHOLNPAIR("Dropped bytes: ", customizedSerial.dropped());
+        #endif
+
+        #if ENABLED(SERIAL_STATS_MAX_RX_QUEUED)
+          SERIAL_ECHOLNPAIR("Max RX Queue Size: ", customizedSerial.rxMaxEnqueued());
+        #endif
+
         ok_to_send();
       }
       else {