diff --git a/libraries/AP_HAL_ChibiOS/hwdef/CubeH7/hwdef.dat b/libraries/AP_HAL_ChibiOS/hwdef/CubeH7/hwdef.dat
index e1366716c9..b7181b20e9 100644
--- a/libraries/AP_HAL_ChibiOS/hwdef/CubeH7/hwdef.dat
+++ b/libraries/AP_HAL_ChibiOS/hwdef/CubeH7/hwdef.dat
@@ -12,6 +12,9 @@ APJ_BOARD_ID 139
 
 FLASH_SIZE_KB 2048
 
+# with 2M flash we can afford to optimize for speed
+env OPTIMIZE -O3
+
 FLASH_RESERVE_START_KB 128
 
 # board voltage
diff --git a/libraries/AP_HAL_ChibiOS/hwdef/Pixhawk4Pro/hwdef.dat b/libraries/AP_HAL_ChibiOS/hwdef/Pixhawk4Pro/hwdef.dat
index 9946809aa5..83cd8c4b49 100644
--- a/libraries/AP_HAL_ChibiOS/hwdef/Pixhawk4Pro/hwdef.dat
+++ b/libraries/AP_HAL_ChibiOS/hwdef/Pixhawk4Pro/hwdef.dat
@@ -12,6 +12,9 @@ APJ_BOARD_ID 139
 
 FLASH_SIZE_KB 2048
 
+# with 2M flash we can afford to optimize for speed
+env OPTIMIZE -O3
+
 # bootloader takes first sector
 FLASH_RESERVE_START_KB 128
 
diff --git a/libraries/AP_HAL_ChibiOS/hwdef/fmuv4/hwdef.dat b/libraries/AP_HAL_ChibiOS/hwdef/fmuv4/hwdef.dat
index 94151a010a..7ece626539 100644
--- a/libraries/AP_HAL_ChibiOS/hwdef/fmuv4/hwdef.dat
+++ b/libraries/AP_HAL_ChibiOS/hwdef/fmuv4/hwdef.dat
@@ -21,6 +21,8 @@ STM32_ST_USE_TIMER 5
 # flash size
 FLASH_SIZE_KB 2048
 
+env OPTIMIZE -O3
+
 # serial port for stdout disabled, use USB console
 # STDOUT_SERIAL SD7
 # STDOUT_BAUDRATE 57600
diff --git a/libraries/AP_HAL_ChibiOS/hwdef/fmuv5/hwdef.dat b/libraries/AP_HAL_ChibiOS/hwdef/fmuv5/hwdef.dat
index 28cecd08f7..2d7a7ff76b 100644
--- a/libraries/AP_HAL_ChibiOS/hwdef/fmuv5/hwdef.dat
+++ b/libraries/AP_HAL_ChibiOS/hwdef/fmuv5/hwdef.dat
@@ -30,6 +30,8 @@ STM32_VDD 330U
 # flash size
 FLASH_SIZE_KB 2048
 
+env OPTIMIZE -O3
+
 # order of UARTs (and USB)
 UART_ORDER OTG1 USART1 USART2 USART3 UART4 USART6 UART7