diff --git a/ports/esp32/boards/ESP32_GENERIC_C6/mpconfigboard.cmake b/ports/esp32/boards/ESP32_GENERIC_C6/mpconfigboard.cmake
index 3060c1cfd9..48946f7094 100644
--- a/ports/esp32/boards/ESP32_GENERIC_C6/mpconfigboard.cmake
+++ b/ports/esp32/boards/ESP32_GENERIC_C6/mpconfigboard.cmake
@@ -2,6 +2,7 @@ set(IDF_TARGET esp32c6)
 
 set(SDKCONFIG_DEFAULTS
     boards/sdkconfig.base
+    boards/sdkconfig.riscv
     boards/sdkconfig.c6
     boards/sdkconfig.ble
 )
diff --git a/ports/esp32/boards/M5STACK_NANOC6/mpconfigboard.cmake b/ports/esp32/boards/M5STACK_NANOC6/mpconfigboard.cmake
index 3060c1cfd9..48946f7094 100644
--- a/ports/esp32/boards/M5STACK_NANOC6/mpconfigboard.cmake
+++ b/ports/esp32/boards/M5STACK_NANOC6/mpconfigboard.cmake
@@ -2,6 +2,7 @@ set(IDF_TARGET esp32c6)
 
 set(SDKCONFIG_DEFAULTS
     boards/sdkconfig.base
+    boards/sdkconfig.riscv
     boards/sdkconfig.c6
     boards/sdkconfig.ble
 )
diff --git a/ports/esp32/boards/UM_TINYC6/mpconfigboard.cmake b/ports/esp32/boards/UM_TINYC6/mpconfigboard.cmake
index 024b1299fa..418bb7ff0f 100644
--- a/ports/esp32/boards/UM_TINYC6/mpconfigboard.cmake
+++ b/ports/esp32/boards/UM_TINYC6/mpconfigboard.cmake
@@ -2,6 +2,7 @@ set(IDF_TARGET esp32c6)
 
 set(SDKCONFIG_DEFAULTS
     boards/sdkconfig.base
+    boards/sdkconfig.riscv
     boards/sdkconfig.c6
     boards/sdkconfig.ble
     boards/UM_TINYC6/sdkconfig.board
diff --git a/ports/esp32/boards/sdkconfig.c6 b/ports/esp32/boards/sdkconfig.c6
index 18e8b75eb4..a90a8f80df 100644
--- a/ports/esp32/boards/sdkconfig.c6
+++ b/ports/esp32/boards/sdkconfig.c6
@@ -1,2 +1,10 @@
 # Workaround for https://github.com/espressif/esp-idf/issues/14456
 CONFIG_ESP_SYSTEM_HW_STACK_GUARD=n
+
+# 802.15.4 not currently supported in MicroPython, disabling saves
+# a little compile time (no difference in binary)
+CONFIG_IEEE802154_ENABLED=n
+
+# Using the SPI flash implementation in ROM saves about 10KB of binary size
+# (and some static RAM)
+CONFIG_SPI_FLASH_ROM_IMPL=y
diff --git a/ports/esp32/boards/sdkconfig.riscv b/ports/esp32/boards/sdkconfig.riscv
new file mode 100644
index 0000000000..fff3ea830b
--- /dev/null
+++ b/ports/esp32/boards/sdkconfig.riscv
@@ -0,0 +1,3 @@
+# ESP RISC-V binary sizes are generally larger than Xtensa ones,
+# so switch to size optimization by default
+CONFIG_COMPILER_OPTIMIZATION_SIZE=y