diff --git a/ports/esp32/boards/ESP32_GENERIC/mpconfigboard.cmake b/ports/esp32/boards/ESP32_GENERIC/mpconfigboard.cmake
index ac60dc8630929..9da09fc081eec 100644
--- a/ports/esp32/boards/ESP32_GENERIC/mpconfigboard.cmake
+++ b/ports/esp32/boards/ESP32_GENERIC/mpconfigboard.cmake
@@ -1,4 +1,4 @@
 set(SDKCONFIG_DEFAULTS
     boards/sdkconfig.base
-    boards/sdkconfig.ble
+    boards/ESP32_GENERIC/sdkconfig.optimize
 )
diff --git a/ports/esp32/boards/ESP32_GENERIC/mpconfigboard.h b/ports/esp32/boards/ESP32_GENERIC/mpconfigboard.h
index 7171a84bb3c7b..1d75fe8a9f6c2 100644
--- a/ports/esp32/boards/ESP32_GENERIC/mpconfigboard.h
+++ b/ports/esp32/boards/ESP32_GENERIC/mpconfigboard.h
@@ -8,3 +8,10 @@
 #ifndef MICROPY_HW_MCU_NAME
 #define MICROPY_HW_MCU_NAME "ESP32"
 #endif
+
+// 禁用藍牙以節省記憶體和韌體空間
+#define MICROPY_PY_BLUETOOTH (0)
+
+// Python heap 設為 80KB，保留更多記憶體給 WiFi/MQTT
+// 180KB 可用記憶體對 Python 應用已經足夠
+#define MICROPY_GC_INITIAL_HEAP_SIZE (80 * 1024)
diff --git a/ports/esp32/boards/ESP32_GENERIC/sdkconfig.optimize b/ports/esp32/boards/ESP32_GENERIC/sdkconfig.optimize
new file mode 100644
index 0000000000000..8f04fb347858c
--- /dev/null
+++ b/ports/esp32/boards/ESP32_GENERIC/sdkconfig.optimize
@@ -0,0 +1,97 @@
+# ESP32 韌體優化設定
+# 目標：禁用藍牙、最大化 WiFi 和 MQTT 性能與穩定性
+
+# ============================================
+# 禁用藍牙功能（釋放約 30-40KB RAM）
+# ============================================
+CONFIG_BT_ENABLED=n
+CONFIG_BT_NIMBLE_ENABLED=n
+CONFIG_BT_CONTROLLER_ENABLED=n
+CONFIG_BT_BLUEDROID_ENABLED=n
+
+# ============================================
+# WiFi 性能優化（優先考慮穩定性）
+# ============================================
+# 大幅增加 WiFi 緩衝區以提供最佳穩定性
+CONFIG_ESP_WIFI_STATIC_RX_BUFFER_NUM=16
+CONFIG_ESP_WIFI_DYNAMIC_RX_BUFFER_NUM=64
+CONFIG_ESP_WIFI_DYNAMIC_TX_BUFFER_NUM=64
+
+# WiFi RX 緩衝區最大長度
+CONFIG_ESP_WIFI_RX_BA_WIN=16
+
+# 啟用 WiFi AMPDU（提高吞吐量）
+CONFIG_ESP_WIFI_AMPDU_TX_ENABLED=y
+CONFIG_ESP_WIFI_AMPDU_RX_ENABLED=y
+
+# WiFi NVS 支援
+CONFIG_ESP_WIFI_NVS_ENABLED=y
+
+# ============================================
+# TCP/IP 協議堆疊優化（針對 MQTT）
+# ============================================
+# 增加 TCP/IP 任務堆疊大小
+CONFIG_LWIP_TCPIP_TASK_STACK_SIZE=4096
+
+# 最大化接收郵箱大小（確保不丟包）
+CONFIG_LWIP_TCP_RECVMBOX_SIZE=32
+CONFIG_LWIP_UDP_RECVMBOX_SIZE=32
+
+# 大幅增加 TCP 發送/接收窗口
+CONFIG_LWIP_TCP_SND_BUF_DEFAULT=16384
+CONFIG_LWIP_TCP_WND_DEFAULT=16384
+
+# TCP MSS 設定
+CONFIG_LWIP_TCP_MSS=1440
+
+# TCP 段重傳超時設定（更積極）
+CONFIG_LWIP_TCP_TMR_INTERVAL=250
+
+# ============================================
+# MQTT 長連接優化
+# ============================================
+# 啟用 TCP 保活機制（對 MQTT 很關鍵）
+CONFIG_LWIP_TCP_KEEPALIVE_DEFAULT=y
+
+# TCP 保活參數（適合 MQTT）
+CONFIG_LWIP_TCP_KEEPIDLE_DEFAULT=7200
+CONFIG_LWIP_TCP_KEEPINTVL_DEFAULT=75
+CONFIG_LWIP_TCP_KEEPCNT_DEFAULT=9
+
+# 增加並發 TCP 連接數
+CONFIG_LWIP_MAX_ACTIVE_TCP=16
+
+# 增加監聽連接數
+CONFIG_LWIP_MAX_LISTENING_TCP=16
+
+# ============================================
+# Socket 選項優化
+# ============================================
+# 啟用 SO_REUSEADDR（快速重連）
+CONFIG_LWIP_SO_REUSE=y
+CONFIG_LWIP_SO_REUSE_RXTOALL=y
+
+# 啟用 SO_RCVBUF（接收緩衝控制）
+CONFIG_LWIP_SO_RCVBUF=y
+
+# ============================================
+# 記憶體管理
+# ============================================
+# 增加 LWIP 記憶體池
+CONFIG_LWIP_MEM_ALLOC_MODE_INTERNAL=y
+
+# DNS 快取大小
+CONFIG_LWIP_DNS_MAX_SERVERS=3
+
+# ============================================
+# 網路效能調整
+# ============================================
+# 啟用 IP 轉發（如果需要）
+# CONFIG_LWIP_IP_FORWARD=n
+
+# 網路緩衝區數量
+CONFIG_LWIP_MAX_SOCKETS=16
+
+# DHCP 選項
+CONFIG_LWIP_DHCP_DOES_ARP_CHECK=y
+CONFIG_LWIP_DHCP_MAX_NTP_SERVERS=3
diff --git a/ports/esp32/boards/ESP32_GENERIC_S3/mpconfigboard.h b/ports/esp32/boards/ESP32_GENERIC_S3/mpconfigboard.h
index c714fe2c227f3..d70c9255da4b7 100644
--- a/ports/esp32/boards/ESP32_GENERIC_S3/mpconfigboard.h
+++ b/ports/esp32/boards/ESP32_GENERIC_S3/mpconfigboard.h
@@ -9,3 +9,6 @@
 
 #define MICROPY_HW_I2C0_SCL                 (9)
 #define MICROPY_HW_I2C0_SDA                 (8)
+
+// Disable I2C target mode due to ESP-IDF v5.3.1 API incompatibility
+#define MICROPY_PY_MACHINE_I2C_TARGET       (0)
diff --git a/ports/esp32/lockfiles/dependencies.lock.esp32 b/ports/esp32/lockfiles/dependencies.lock.esp32
index 71eccf03201bc..f1f2b34e4de3f 100644
--- a/ports/esp32/lockfiles/dependencies.lock.esp32
+++ b/ports/esp32/lockfiles/dependencies.lock.esp32
@@ -25,7 +25,7 @@ dependencies:
   idf:
     source:
       type: idf
-    version: 5.5.1
+    version: 5.3.1
 direct_dependencies:
 - espressif/lan867x
 - espressif/mdns
diff --git a/ports/esp32/lockfiles/dependencies.lock.esp32s3 b/ports/esp32/lockfiles/dependencies.lock.esp32s3
index 38c17f5d6252a..7ec41743ed2f7 100644
--- a/ports/esp32/lockfiles/dependencies.lock.esp32s3
+++ b/ports/esp32/lockfiles/dependencies.lock.esp32s3
@@ -40,7 +40,7 @@ dependencies:
   idf:
     source:
       type: idf
-    version: 5.5.1
+    version: 5.3.1
 direct_dependencies:
 - espressif/esp_tinyusb
 - espressif/mdns
diff --git a/ports/esp32/machine_timer.c b/ports/esp32/machine_timer.c
index ea9ce5469b0b7..a6016ebf03db4 100644
--- a/ports/esp32/machine_timer.c
+++ b/ports/esp32/machine_timer.c
@@ -180,7 +180,7 @@ void machine_timer_enable(machine_timer_obj_t *self) {
     }
 
     timer_ll_enable_counter(self->hal_context.dev, self->index, false);
-    esp_clk_tree_enable_src(TIMER_CLK_SRC, true);
+    // esp_clk_tree_enable_src(TIMER_CLK_SRC, true);  // 在 ESP-IDF 5.3.1 中此函數不可用，時鐘源由 LL 層管理
     #if ESP_IDF_VERSION < ESP_IDF_VERSION_VAL(5, 5, 0)
     timer_ll_set_clock_source(self->hal_context.dev, self->index, TIMER_CLK_SRC);
     timer_ll_enable_clock(self->hal_context.dev, self->index, true);