diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 7ccd4ce7..02c117cd 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -744,7 +744,7 @@ link_directories(
 )
 
 
-set(COMMON_FLAGS -MP -MD -mthumb -mabi=aapcs -Wall -Wno-unknown-pragmas -g3 -ffunction-sections -fdata-sections -fno-strict-aliasing -fno-builtin --short-enums -mcpu=cortex-m4 -mfloat-abi=hard -mfpu=fpv4-sp-d16 -Wreturn-type -Werror=return-type)
+set(COMMON_FLAGS -MP -MD -mthumb -mabi=aapcs -Wall -Wno-unknown-pragmas -g3 -ffunction-sections -fdata-sections -fno-strict-aliasing -fno-builtin --short-enums -mcpu=cortex-m4 -mfloat-abi=hard -mfpu=fpv4-sp-d16 -Wreturn-type -Werror=return-type -fstack-usage -fno-exceptions -fno-non-call-exceptions)
 add_definitions(-DCONFIG_GPIO_AS_PINRESET)
 add_definitions(-DDEBUG)
 add_definitions(-DNIMBLE_CFG_CONTROLLER)
@@ -765,9 +765,9 @@ target_include_directories(nrf-sdk SYSTEM PUBLIC . ../)
 target_include_directories(nrf-sdk SYSTEM PUBLIC ${INCLUDES_FROM_LIBS})
 target_compile_options(nrf-sdk PRIVATE
         $<$<AND:$<COMPILE_LANGUAGE:C>,$<CONFIG:DEBUG>>: ${COMMON_FLAGS} -O0 -g3>
-        $<$<AND:$<COMPILE_LANGUAGE:C>,$<CONFIG:RELEASE>>: ${COMMON_FLAGS} -O3>
-        $<$<AND:$<COMPILE_LANGUAGE:CXX>,$<CONFIG:DEBUG>>: ${COMMON_FLAGS} -O0>
-        $<$<AND:$<COMPILE_LANGUAGE:CXX>,$<CONFIG:RELEASE>>: ${COMMON_FLAGS} -O3>
+        $<$<AND:$<COMPILE_LANGUAGE:C>,$<CONFIG:RELEASE>>: ${COMMON_FLAGS} -Os>
+        $<$<AND:$<COMPILE_LANGUAGE:CXX>,$<CONFIG:DEBUG>>: ${COMMON_FLAGS} -O0 -fno-rtti>
+        $<$<AND:$<COMPILE_LANGUAGE:CXX>,$<CONFIG:RELEASE>>: ${COMMON_FLAGS} -Os -fno-rtti>
         $<$<COMPILE_LANGUAGE:ASM>: -MP -MD -x assembler-with-cpp>
         )
 
@@ -777,9 +777,9 @@ target_include_directories(nimble SYSTEM PUBLIC . ../)
 target_include_directories(nimble SYSTEM PUBLIC ${INCLUDES_FROM_LIBS})
 target_compile_options(nimble PRIVATE
         $<$<AND:$<COMPILE_LANGUAGE:C>,$<CONFIG:DEBUG>>: ${COMMON_FLAGS} -O0 -g3 -Wno-unused-but-set-variable -Wno-maybe-uninitialized>
-        $<$<AND:$<COMPILE_LANGUAGE:C>,$<CONFIG:RELEASE>>: ${COMMON_FLAGS} -O3 -Wno-unused-but-set-variable -Wno-maybe-uninitialized>
-        $<$<AND:$<COMPILE_LANGUAGE:CXX>,$<CONFIG:DEBUG>>: ${COMMON_FLAGS} -O0 -g3 -Wno-unused-but-set-variable -Wno-maybe-uninitialized>
-        $<$<AND:$<COMPILE_LANGUAGE:CXX>,$<CONFIG:RELEASE>>: ${COMMON_FLAGS} -O3 -Wno-unused-but-set-variable -Wno-maybe-uninitialized>
+        $<$<AND:$<COMPILE_LANGUAGE:C>,$<CONFIG:RELEASE>>: ${COMMON_FLAGS} -Os -Wno-unused-but-set-variable -Wno-maybe-uninitialized>
+        $<$<AND:$<COMPILE_LANGUAGE:CXX>,$<CONFIG:DEBUG>>: ${COMMON_FLAGS} -O0 -g3 -Wno-unused-but-set-variable -Wno-maybe-uninitialized -fno-rtti>
+        $<$<AND:$<COMPILE_LANGUAGE:CXX>,$<CONFIG:RELEASE>>: ${COMMON_FLAGS} -Os -Wno-unused-but-set-variable -Wno-maybe-uninitialized -fno-rtti>
         $<$<COMPILE_LANGUAGE:ASM>: -MP -MD -x assembler-with-cpp>
         )
 
@@ -789,9 +789,9 @@ target_include_directories(lvgl SYSTEM PUBLIC . ../)
 target_include_directories(lvgl SYSTEM PUBLIC ${INCLUDES_FROM_LIBS})
 target_compile_options(lvgl PRIVATE
         $<$<AND:$<COMPILE_LANGUAGE:C>,$<CONFIG:DEBUG>>: ${COMMON_FLAGS} -O0 -g3>
-        $<$<AND:$<COMPILE_LANGUAGE:C>,$<CONFIG:RELEASE>>: ${COMMON_FLAGS} -O3>
-        $<$<AND:$<COMPILE_LANGUAGE:CXX>,$<CONFIG:DEBUG>>: ${COMMON_FLAGS} -O0 -g3>
-        $<$<AND:$<COMPILE_LANGUAGE:CXX>,$<CONFIG:RELEASE>>: ${COMMON_FLAGS} -O3>
+        $<$<AND:$<COMPILE_LANGUAGE:C>,$<CONFIG:RELEASE>>: ${COMMON_FLAGS} -Os>
+        $<$<AND:$<COMPILE_LANGUAGE:CXX>,$<CONFIG:DEBUG>>: ${COMMON_FLAGS} -O0 -g3 -fno-rtti>
+        $<$<AND:$<COMPILE_LANGUAGE:CXX>,$<CONFIG:RELEASE>>: ${COMMON_FLAGS} -Os -fno-rtti>
         $<$<COMPILE_LANGUAGE:ASM>: -MP -MD -x assembler-with-cpp>
         )
 
@@ -804,9 +804,9 @@ set_target_properties(${EXECUTABLE_NAME} PROPERTIES OUTPUT_NAME ${EXECUTABLE_FIL
 target_link_libraries(${EXECUTABLE_NAME} nimble nrf-sdk lvgl)
 target_compile_options(${EXECUTABLE_NAME} PUBLIC
         $<$<AND:$<COMPILE_LANGUAGE:C>,$<CONFIG:DEBUG>>: ${COMMON_FLAGS} -O0 -g3>
-        $<$<AND:$<COMPILE_LANGUAGE:C>,$<CONFIG:RELEASE>>: ${COMMON_FLAGS} -O3>
-        $<$<AND:$<COMPILE_LANGUAGE:CXX>,$<CONFIG:DEBUG>>: ${COMMON_FLAGS} -O0 -g3>
-        $<$<AND:$<COMPILE_LANGUAGE:CXX>,$<CONFIG:RELEASE>>: ${COMMON_FLAGS} -O3>
+        $<$<AND:$<COMPILE_LANGUAGE:C>,$<CONFIG:RELEASE>>: ${COMMON_FLAGS} -Os>
+        $<$<AND:$<COMPILE_LANGUAGE:CXX>,$<CONFIG:DEBUG>>: ${COMMON_FLAGS} -O0 -g3 -fno-rtti>
+        $<$<AND:$<COMPILE_LANGUAGE:CXX>,$<CONFIG:RELEASE>>: ${COMMON_FLAGS} -Os -fno-rtti>
         $<$<COMPILE_LANGUAGE:ASM>: -MP -MD -x assembler-with-cpp>
         )
 
@@ -834,9 +834,9 @@ target_link_libraries(${EXECUTABLE_MCUBOOT_NAME} nimble nrf-sdk lvgl)
 set_target_properties(${EXECUTABLE_MCUBOOT_NAME} PROPERTIES OUTPUT_NAME ${EXECUTABLE_MCUBOOT_FILE_NAME})
 target_compile_options(${EXECUTABLE_MCUBOOT_NAME} PUBLIC
         $<$<AND:$<COMPILE_LANGUAGE:C>,$<CONFIG:DEBUG>>: ${COMMON_FLAGS} -O0 -g3>
-        $<$<AND:$<COMPILE_LANGUAGE:C>,$<CONFIG:RELEASE>>: ${COMMON_FLAGS} -O3>
-        $<$<AND:$<COMPILE_LANGUAGE:CXX>,$<CONFIG:DEBUG>>: ${COMMON_FLAGS} -O0 -g3>
-        $<$<AND:$<COMPILE_LANGUAGE:CXX>,$<CONFIG:RELEASE>>: ${COMMON_FLAGS} -O3>
+        $<$<AND:$<COMPILE_LANGUAGE:C>,$<CONFIG:RELEASE>>: ${COMMON_FLAGS} -Os>
+        $<$<AND:$<COMPILE_LANGUAGE:CXX>,$<CONFIG:DEBUG>>: ${COMMON_FLAGS} -O0 -g3 -fno-rtti>
+        $<$<AND:$<COMPILE_LANGUAGE:CXX>,$<CONFIG:RELEASE>>: ${COMMON_FLAGS} -Os -fno-rtti>
         $<$<COMPILE_LANGUAGE:ASM>: -MP -MD -x assembler-with-cpp>
         )
 
@@ -871,9 +871,9 @@ set_target_properties(${EXECUTABLE_RECOVERY_NAME} PROPERTIES OUTPUT_NAME ${EXECU
 target_compile_definitions(${EXECUTABLE_RECOVERY_NAME} PUBLIC "PINETIME_IS_RECOVERY")
 target_compile_options(${EXECUTABLE_RECOVERY_NAME} PUBLIC
         $<$<AND:$<COMPILE_LANGUAGE:C>,$<CONFIG:DEBUG>>: ${COMMON_FLAGS} -O0 -g3>
-        $<$<AND:$<COMPILE_LANGUAGE:C>,$<CONFIG:RELEASE>>: ${COMMON_FLAGS} -O3>
-        $<$<AND:$<COMPILE_LANGUAGE:CXX>,$<CONFIG:DEBUG>>: ${COMMON_FLAGS} -O0 -g3>
-        $<$<AND:$<COMPILE_LANGUAGE:CXX>,$<CONFIG:RELEASE>>: ${COMMON_FLAGS} -O3>
+        $<$<AND:$<COMPILE_LANGUAGE:C>,$<CONFIG:RELEASE>>: ${COMMON_FLAGS} -Os>
+        $<$<AND:$<COMPILE_LANGUAGE:CXX>,$<CONFIG:DEBUG>>: ${COMMON_FLAGS} -O0 -g3 -fno-rtti>
+        $<$<AND:$<COMPILE_LANGUAGE:CXX>,$<CONFIG:RELEASE>>: ${COMMON_FLAGS} -Os -fno-rtti>
         $<$<COMPILE_LANGUAGE:ASM>: -MP -MD -x assembler-with-cpp>
         )
 
@@ -901,9 +901,9 @@ set_target_properties(${EXECUTABLE_RECOVERY_MCUBOOT_NAME} PROPERTIES OUTPUT_NAME
 target_compile_definitions(${EXECUTABLE_RECOVERY_MCUBOOT_NAME} PUBLIC "PINETIME_IS_RECOVERY")
 target_compile_options(${EXECUTABLE_RECOVERY_MCUBOOT_NAME} PUBLIC
         $<$<AND:$<COMPILE_LANGUAGE:C>,$<CONFIG:DEBUG>>: ${COMMON_FLAGS} -O0 -g3>
-        $<$<AND:$<COMPILE_LANGUAGE:C>,$<CONFIG:RELEASE>>: ${COMMON_FLAGS} -O3>
-        $<$<AND:$<COMPILE_LANGUAGE:CXX>,$<CONFIG:DEBUG>>: ${COMMON_FLAGS} -O0 -g3>
-        $<$<AND:$<COMPILE_LANGUAGE:CXX>,$<CONFIG:RELEASE>>: ${COMMON_FLAGS} -O3>
+        $<$<AND:$<COMPILE_LANGUAGE:C>,$<CONFIG:RELEASE>>: ${COMMON_FLAGS} -Os>
+        $<$<AND:$<COMPILE_LANGUAGE:CXX>,$<CONFIG:DEBUG>>: ${COMMON_FLAGS} -O0 -g3 -fno-rtti>
+        $<$<AND:$<COMPILE_LANGUAGE:CXX>,$<CONFIG:RELEASE>>: ${COMMON_FLAGS} -Os -fno-rtti>
         $<$<COMPILE_LANGUAGE:ASM>: -MP -MD -x assembler-with-cpp>
         )
 
@@ -938,9 +938,9 @@ target_link_libraries(${EXECUTABLE_RECOVERYLOADER_NAME} nrf-sdk)
 set_target_properties(${EXECUTABLE_RECOVERYLOADER_NAME} PROPERTIES OUTPUT_NAME ${EXECUTABLE_RECOVERYLOADER_FILE_NAME})
 target_compile_options(${EXECUTABLE_RECOVERYLOADER_NAME} PUBLIC
         $<$<AND:$<COMPILE_LANGUAGE:C>,$<CONFIG:DEBUG>>: ${COMMON_FLAGS} -O0 -g3>
-        $<$<AND:$<COMPILE_LANGUAGE:C>,$<CONFIG:RELEASE>>: ${COMMON_FLAGS} -O3>
-        $<$<AND:$<COMPILE_LANGUAGE:CXX>,$<CONFIG:DEBUG>>: ${COMMON_FLAGS} -O0 -g3>
-        $<$<AND:$<COMPILE_LANGUAGE:CXX>,$<CONFIG:RELEASE>>: ${COMMON_FLAGS} -O3>
+        $<$<AND:$<COMPILE_LANGUAGE:C>,$<CONFIG:RELEASE>>: ${COMMON_FLAGS} -Os>
+        $<$<AND:$<COMPILE_LANGUAGE:CXX>,$<CONFIG:DEBUG>>: ${COMMON_FLAGS} -O0 -g3 -fno-rtti>
+        $<$<AND:$<COMPILE_LANGUAGE:CXX>,$<CONFIG:RELEASE>>: ${COMMON_FLAGS} -Os -fno-rtti>
         $<$<COMPILE_LANGUAGE:ASM>: -MP -MD -x assembler-with-cpp>
         )
 target_include_directories(${EXECUTABLE_RECOVERYLOADER_NAME} PUBLIC
@@ -971,9 +971,9 @@ target_link_libraries(${EXECUTABLE_MCUBOOT_RECOVERYLOADER_NAME} nrf-sdk)
 set_target_properties(${EXECUTABLE_MCUBOOT_RECOVERYLOADER_NAME} PROPERTIES OUTPUT_NAME ${EXECUTABLE_MCUBOOT_RECOVERYLOADER_FILE_NAME})
 target_compile_options(${EXECUTABLE_MCUBOOT_RECOVERYLOADER_NAME} PUBLIC
         $<$<AND:$<COMPILE_LANGUAGE:C>,$<CONFIG:DEBUG>>: ${COMMON_FLAGS} -O0 -g3>
-        $<$<AND:$<COMPILE_LANGUAGE:C>,$<CONFIG:RELEASE>>: ${COMMON_FLAGS} -O3>
-        $<$<AND:$<COMPILE_LANGUAGE:CXX>,$<CONFIG:DEBUG>>: ${COMMON_FLAGS} -O0 -g3>
-        $<$<AND:$<COMPILE_LANGUAGE:CXX>,$<CONFIG:RELEASE>>: ${COMMON_FLAGS} -O3>
+        $<$<AND:$<COMPILE_LANGUAGE:C>,$<CONFIG:RELEASE>>: ${COMMON_FLAGS} -Os>
+        $<$<AND:$<COMPILE_LANGUAGE:CXX>,$<CONFIG:DEBUG>>: ${COMMON_FLAGS} -O0 -g3 -fno-rtti>
+        $<$<AND:$<COMPILE_LANGUAGE:CXX>,$<CONFIG:RELEASE>>: ${COMMON_FLAGS} -Os -fno-rtti>
         $<$<COMPILE_LANGUAGE:ASM>: -MP -MD -x assembler-with-cpp>
         )
 target_include_directories(${EXECUTABLE_MCUBOOT_RECOVERYLOADER_NAME} PUBLIC
diff --git a/src/displayapp/DisplayApp.cpp b/src/displayapp/DisplayApp.cpp
index 419b9f6f..7b03d569 100644
--- a/src/displayapp/DisplayApp.cpp
+++ b/src/displayapp/DisplayApp.cpp
@@ -153,7 +153,7 @@ void DisplayApp::Refresh() {
         break;
       case Messages::TimerDone:
         if (currentApp == Apps::Timer) {
-          auto *timer = dynamic_cast<Screens::Timer*>(currentScreen.get());
+          auto *timer = static_cast<Screens::Timer*>(currentScreen.get());
           timer->setDone();
         } else {
           LoadApp(Apps::Timer, DisplayApp::FullRefreshDirections::Down);