diff --git a/assets/compiled/gpio.pb.c b/assets/compiled/gpio.pb.c
deleted file mode 100644
index a47c928d..00000000
--- a/assets/compiled/gpio.pb.c
+++ /dev/null
@@ -1,33 +0,0 @@
-/* Automatically generated nanopb constant definitions */
-/* Generated by nanopb-0.4.5 */
-
-#include "gpio.pb.h"
-#if PB_PROTO_HEADER_VERSION != 40
-#error Regenerate this file with the current version of nanopb generator.
-#endif
-
-PB_BIND(PB_Gpio_SetPinMode, PB_Gpio_SetPinMode, AUTO)
-
-
-PB_BIND(PB_Gpio_SetInputPull, PB_Gpio_SetInputPull, AUTO)
-
-
-PB_BIND(PB_Gpio_GetPinMode, PB_Gpio_GetPinMode, AUTO)
-
-
-PB_BIND(PB_Gpio_GetPinModeResponse, PB_Gpio_GetPinModeResponse, AUTO)
-
-
-PB_BIND(PB_Gpio_ReadPin, PB_Gpio_ReadPin, AUTO)
-
-
-PB_BIND(PB_Gpio_ReadPinResponse, PB_Gpio_ReadPinResponse, AUTO)
-
-
-PB_BIND(PB_Gpio_WritePin, PB_Gpio_WritePin, AUTO)
-
-
-
-
-
-
diff --git a/assets/compiled/gpio.pb.h b/assets/compiled/gpio.pb.h
deleted file mode 100644
index a8a08df7..00000000
--- a/assets/compiled/gpio.pb.h
+++ /dev/null
@@ -1,183 +0,0 @@
-/* Automatically generated nanopb header */
-/* Generated by nanopb-0.4.5 */
-
-#ifndef PB_PB_GPIO_GPIO_PB_H_INCLUDED
-#define PB_PB_GPIO_GPIO_PB_H_INCLUDED
-#include <pb.h>
-
-#if PB_PROTO_HEADER_VERSION != 40
-#error Regenerate this file with the current version of nanopb generator.
-#endif
-
-/* Enum definitions */
-typedef enum _PB_Gpio_GpioPin { 
-    PB_Gpio_GpioPin_PC0 = 0, 
-    PB_Gpio_GpioPin_PC1 = 1, 
-    PB_Gpio_GpioPin_PC3 = 2, 
-    PB_Gpio_GpioPin_PB2 = 3, 
-    PB_Gpio_GpioPin_PB3 = 4, 
-    PB_Gpio_GpioPin_PA4 = 5, 
-    PB_Gpio_GpioPin_PA6 = 6, 
-    PB_Gpio_GpioPin_PA7 = 7 
-} PB_Gpio_GpioPin;
-
-typedef enum _PB_Gpio_GpioPinMode { 
-    PB_Gpio_GpioPinMode_OUTPUT = 0, 
-    PB_Gpio_GpioPinMode_INPUT = 1 
-} PB_Gpio_GpioPinMode;
-
-typedef enum _PB_Gpio_GpioInputPull { 
-    PB_Gpio_GpioInputPull_NO = 0, 
-    PB_Gpio_GpioInputPull_UP = 1, 
-    PB_Gpio_GpioInputPull_DOWN = 2
-} PB_Gpio_GpioInputPull;
-
-/* Struct definitions */
-typedef struct _PB_Gpio_GetPinMode { 
-    PB_Gpio_GpioPin pin; 
-} PB_Gpio_GetPinMode;
-
-typedef struct _PB_Gpio_GetPinModeResponse { 
-    PB_Gpio_GpioPinMode mode; 
-} PB_Gpio_GetPinModeResponse;
-
-typedef struct _PB_Gpio_ReadPin { 
-    PB_Gpio_GpioPin pin; 
-} PB_Gpio_ReadPin;
-
-typedef struct _PB_Gpio_ReadPinResponse { 
-    uint32_t value; 
-} PB_Gpio_ReadPinResponse;
-
-typedef struct _PB_Gpio_SetInputPull { 
-    PB_Gpio_GpioPin pin; 
-    PB_Gpio_GpioInputPull pull_mode; 
-} PB_Gpio_SetInputPull;
-
-typedef struct _PB_Gpio_SetPinMode { 
-    PB_Gpio_GpioPin pin; 
-    PB_Gpio_GpioPinMode mode; 
-} PB_Gpio_SetPinMode;
-
-typedef struct _PB_Gpio_WritePin { 
-    PB_Gpio_GpioPin pin; 
-    uint32_t value; 
-} PB_Gpio_WritePin;
-
-
-/* Helper constants for enums */
-#define _PB_Gpio_GpioPin_MIN PB_Gpio_GpioPin_PC0
-#define _PB_Gpio_GpioPin_MAX PB_Gpio_GpioPin_PA7
-#define _PB_Gpio_GpioPin_ARRAYSIZE ((PB_Gpio_GpioPin)(PB_Gpio_GpioPin_PA7+1))
-
-#define _PB_Gpio_GpioPinMode_MIN PB_Gpio_GpioPinMode_OUTPUT
-#define _PB_Gpio_GpioPinMode_MAX PB_Gpio_GpioPinMode_INPUT
-#define _PB_Gpio_GpioPinMode_ARRAYSIZE ((PB_Gpio_GpioPinMode)(PB_Gpio_GpioPinMode_INPUT+1))
-
-#define _PB_Gpio_GpioInputPull_MIN PB_Gpio_GpioInputPull_NO
-#define _PB_Gpio_GpioInputPull_MAX PB_Gpio_GpioInputPull_DOWN
-#define _PB_Gpio_GpioInputPull_ARRAYSIZE ((PB_Gpio_GpioInputPull)(PB_Gpio_GpioInputPull_DOWN+1))
-
-
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-/* Initializer values for message structs */
-#define PB_Gpio_SetPinMode_init_default          {_PB_Gpio_GpioPin_MIN, _PB_Gpio_GpioPinMode_MIN}
-#define PB_Gpio_SetInputPull_init_default        {_PB_Gpio_GpioPin_MIN, _PB_Gpio_GpioInputPull_MIN}
-#define PB_Gpio_GetPinMode_init_default          {_PB_Gpio_GpioPin_MIN}
-#define PB_Gpio_GetPinModeResponse_init_default  {_PB_Gpio_GpioPinMode_MIN}
-#define PB_Gpio_ReadPin_init_default             {_PB_Gpio_GpioPin_MIN}
-#define PB_Gpio_ReadPinResponse_init_default     {0}
-#define PB_Gpio_WritePin_init_default            {_PB_Gpio_GpioPin_MIN, 0}
-#define PB_Gpio_SetPinMode_init_zero             {_PB_Gpio_GpioPin_MIN, _PB_Gpio_GpioPinMode_MIN}
-#define PB_Gpio_SetInputPull_init_zero           {_PB_Gpio_GpioPin_MIN, _PB_Gpio_GpioInputPull_MIN}
-#define PB_Gpio_GetPinMode_init_zero             {_PB_Gpio_GpioPin_MIN}
-#define PB_Gpio_GetPinModeResponse_init_zero     {_PB_Gpio_GpioPinMode_MIN}
-#define PB_Gpio_ReadPin_init_zero                {_PB_Gpio_GpioPin_MIN}
-#define PB_Gpio_ReadPinResponse_init_zero        {0}
-#define PB_Gpio_WritePin_init_zero               {_PB_Gpio_GpioPin_MIN, 0}
-
-/* Field tags (for use in manual encoding/decoding) */
-#define PB_Gpio_GetPinMode_pin_tag               1
-#define PB_Gpio_GetPinModeResponse_mode_tag      1
-#define PB_Gpio_ReadPin_pin_tag                  1
-#define PB_Gpio_ReadPinResponse_value_tag        2
-#define PB_Gpio_SetInputPull_pin_tag             1
-#define PB_Gpio_SetInputPull_pull_mode_tag       2
-#define PB_Gpio_SetPinMode_pin_tag               1
-#define PB_Gpio_SetPinMode_mode_tag              2
-#define PB_Gpio_WritePin_pin_tag                 1
-#define PB_Gpio_WritePin_value_tag               2
-
-/* Struct field encoding specification for nanopb */
-#define PB_Gpio_SetPinMode_FIELDLIST(X, a) \
-X(a, STATIC,   SINGULAR, UENUM,    pin,               1) \
-X(a, STATIC,   SINGULAR, UENUM,    mode,              2)
-#define PB_Gpio_SetPinMode_CALLBACK NULL
-#define PB_Gpio_SetPinMode_DEFAULT NULL
-
-#define PB_Gpio_SetInputPull_FIELDLIST(X, a) \
-X(a, STATIC,   SINGULAR, UENUM,    pin,               1) \
-X(a, STATIC,   SINGULAR, UENUM,    pull_mode,         2)
-#define PB_Gpio_SetInputPull_CALLBACK NULL
-#define PB_Gpio_SetInputPull_DEFAULT NULL
-
-#define PB_Gpio_GetPinMode_FIELDLIST(X, a) \
-X(a, STATIC,   SINGULAR, UENUM,    pin,               1)
-#define PB_Gpio_GetPinMode_CALLBACK NULL
-#define PB_Gpio_GetPinMode_DEFAULT NULL
-
-#define PB_Gpio_GetPinModeResponse_FIELDLIST(X, a) \
-X(a, STATIC,   SINGULAR, UENUM,    mode,              1)
-#define PB_Gpio_GetPinModeResponse_CALLBACK NULL
-#define PB_Gpio_GetPinModeResponse_DEFAULT NULL
-
-#define PB_Gpio_ReadPin_FIELDLIST(X, a) \
-X(a, STATIC,   SINGULAR, UENUM,    pin,               1)
-#define PB_Gpio_ReadPin_CALLBACK NULL
-#define PB_Gpio_ReadPin_DEFAULT NULL
-
-#define PB_Gpio_ReadPinResponse_FIELDLIST(X, a) \
-X(a, STATIC,   SINGULAR, UINT32,   value,             2)
-#define PB_Gpio_ReadPinResponse_CALLBACK NULL
-#define PB_Gpio_ReadPinResponse_DEFAULT NULL
-
-#define PB_Gpio_WritePin_FIELDLIST(X, a) \
-X(a, STATIC,   SINGULAR, UENUM,    pin,               1) \
-X(a, STATIC,   SINGULAR, UINT32,   value,             2)
-#define PB_Gpio_WritePin_CALLBACK NULL
-#define PB_Gpio_WritePin_DEFAULT NULL
-
-extern const pb_msgdesc_t PB_Gpio_SetPinMode_msg;
-extern const pb_msgdesc_t PB_Gpio_SetInputPull_msg;
-extern const pb_msgdesc_t PB_Gpio_GetPinMode_msg;
-extern const pb_msgdesc_t PB_Gpio_GetPinModeResponse_msg;
-extern const pb_msgdesc_t PB_Gpio_ReadPin_msg;
-extern const pb_msgdesc_t PB_Gpio_ReadPinResponse_msg;
-extern const pb_msgdesc_t PB_Gpio_WritePin_msg;
-
-/* Defines for backwards compatibility with code written before nanopb-0.4.0 */
-#define PB_Gpio_SetPinMode_fields &PB_Gpio_SetPinMode_msg
-#define PB_Gpio_SetInputPull_fields &PB_Gpio_SetInputPull_msg
-#define PB_Gpio_GetPinMode_fields &PB_Gpio_GetPinMode_msg
-#define PB_Gpio_GetPinModeResponse_fields &PB_Gpio_GetPinModeResponse_msg
-#define PB_Gpio_ReadPin_fields &PB_Gpio_ReadPin_msg
-#define PB_Gpio_ReadPinResponse_fields &PB_Gpio_ReadPinResponse_msg
-#define PB_Gpio_WritePin_fields &PB_Gpio_WritePin_msg
-
-/* Maximum encoded size of messages (where known) */
-#define PB_Gpio_GetPinModeResponse_size          2
-#define PB_Gpio_GetPinMode_size                  2
-#define PB_Gpio_ReadPinResponse_size             6
-#define PB_Gpio_ReadPin_size                     2
-#define PB_Gpio_SetInputPull_size                4
-#define PB_Gpio_SetPinMode_size                  4
-#define PB_Gpio_WritePin_size                    8
-
-#ifdef __cplusplus
-} /* extern "C" */
-#endif
-
-#endif
diff --git a/documentation/fbt.md b/documentation/fbt.md
index 48d761f5..a1e92849 100644
--- a/documentation/fbt.md
+++ b/documentation/fbt.md
@@ -10,7 +10,10 @@ Make sure that `gcc-arm-none-eabi` toolchain & OpenOCD executables are in system
 
 ## NB
 
-FBT constructs all referenced environments & their targets' dependency trees on startup. So, to keep startup time as low as possible, we're hiding construction of certain targets behind command-line options.
+* `fbt` constructs all referenced environments & their targets' dependency trees on startup. So, to keep startup time as low as possible, we're hiding construction of certain targets behind command-line options.
+* `fbt` always performs `git submodule update --init` on start, unless you set `FBT_NO_SYNC=1` in environment:
+    * On Windows, that's `set "FBT_NO_SYNC=1"` in the shell you're running `fbt` from
+    * On \*nix, it's `$ FBT_NO_SYNC=1 ./fbt ...`
 
 ## Invoking FBT
 
diff --git a/fbt b/fbt
index 47444aa7..b3d2ca35 100755
--- a/fbt
+++ b/fbt
@@ -5,12 +5,13 @@ set -e
 SCRIPTDIR="$( dirname -- "$0"; )";
 SCONS_EP=${SCRIPTDIR}/lib/scons/scripts/scons.py
 
-if [[ -d .git ]]; then
-    git submodule update --init
-else # Not in a git repo
-    echo Not in a git repo, please clone with git clone --recursive
-    # Return error code 1 to indicate failure
-    exit 1
+if [[ -z "${FBT_NO_SYNC:-}" ]] ; then
+    if [[ -d .git ]]; then
+        git submodule update --init
+    else
+        echo Not in a git repo, please clone with git clone --recursive
+        exit 1
+    fi
 fi
 
 SCONS_DEFAULT_FLAGS="-Q --warn=target-not-built"
diff --git a/fbt.cmd b/fbt.cmd
index cecab465..5edecd21 100644
--- a/fbt.cmd
+++ b/fbt.cmd
@@ -2,8 +2,13 @@
 
 set SCONS_EP=%~dp0\lib\scons\scripts\scons.py
 
-if exist ".git" (
-	git submodule update --init
+if [%FBT_NO_SYNC%] == [] (
+	if exist ".git" (
+		git submodule update --init
+	) else (
+		echo Not in a git repo, please clone with git clone --recursive
+		exit /b 1
+	)
 )
 
 set "SCONS_DEFAULT_FLAGS=-Q --warn=target-not-built"