diff --git a/CMakeLists.txt b/CMakeLists.txt
index 0d1b50722..73002a842 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1330,18 +1330,13 @@ if (CMAKE_COMPILER_IS_GNUCC OR CMAKE_COMPILER_IS_GNUCXX OR (CMAKE_C_COMPILER_ID
                 set(VISIBILITY_FLAG -fvisibility=hidden)
     endif()
     if (LWS_WITH_GCOV)
-	    set (GCOV_FLAGS "-fprofile-arcs -ftest-coverage -O0")
+	    set (GCOV_FLAGS "-fprofile-arcs -ftest-coverage ")
     endif()
 
 	if (LWS_WITH_ASAN)
 		set (ASAN_FLAGS "-fsanitize=address -fsanitize=pointer-compare -fsanitize=pointer-subtract -fsanitize=leak -fsanitize=undefined -fsanitize-address-use-after-scope -fsanitize-undefined-trap-on-error")
 		message("Enabling ASAN")
 	endif()
-    if (CMAKE_BUILD_TYPE MATCHES "DEBUG")
-		set(CMAKE_C_FLAGS "-O0 ${CMAKE_C_FLAGS}")
-    else()
-		set(CMAKE_C_FLAGS "-O3 ${CMAKE_C_FLAGS}")
-    endif()
 
     if (UNIX AND NOT LWS_WITH_ESP32)
 	    set(CMAKE_C_FLAGS "-Wall -Wsign-compare -Wignored-qualifiers -Wtype-limits -Wuninitialized -Werror ${VISIBILITY_FLAG} -Wundef ${GCOV_FLAGS} ${CMAKE_C_FLAGS} ${ASAN_FLAGS}" )
diff --git a/contrib/cross-aarch64.cmake b/contrib/cross-aarch64.cmake
index 518150191..8f36fc389 100644
--- a/contrib/cross-aarch64.cmake
+++ b/contrib/cross-aarch64.cmake
@@ -14,6 +14,22 @@ set(CMAKE_SYSTEM_PROCESSOR aarch64)
 set(CMAKE_C_COMPILER "aarch64-linux-gnu-gcc")
 set(CMAKE_CXX_COMPILER "aarch64-linux-gnu-g++")
 
+#
+# Different build system distros set release optimization level to different
+# things according to their local policy, eg, Fedora is -O2 and Ubuntu is -O3
+# here.  Actually the build system's local policy is completely unrelated to
+# our desire for cross-build release optimization policy for code built to run
+# on a completely different target than the build system itself.
+#
+# Since this goes last on the compiler commandline we have to override it to a
+# sane value for cross-build here.  Notice some gcc versions enable broken
+# optimizations with -O3.
+#
+if (CMAKE_BUILD_TYPE MATCHES RELEASE OR CMAKE_BUILD_TYPE MATCHES Release OR CMAKE_BUILD_TYPE MATCHES release)
+	set(CMAKE_C_FLAGS_RELEASE ${CMAKE_C_FLAGS_RELEASE}" -O2")
+	set(CMAKE_CXX_FLAGS_RELEASE ${CMAKE_CXX_FLAGS_RELEASE}" -O2")
+endif()
+
 #-nostdlib
 SET(CMAKE_C_FLAGS "-DGCC_VER=\"\\\"$(GCC_VER)\\\"\" -DARM64=1 -D__LP64__=1 -Os -g3 -fpie -mstrict-align -DOPTEE_DEV_KIT=../../../../out/arm-plat-hikey/export-ta_arm64/include -I../../../../lib/libutee/include  -fPIC -ffunction-sections -fdata-sections -I../../../../core/include" CACHE STRING "" FORCE)
 
diff --git a/contrib/cross-arm-android-gnueabi.cmake b/contrib/cross-arm-android-gnueabi.cmake
index e99e6f65d..f0a18a54a 100644
--- a/contrib/cross-arm-android-gnueabi.cmake
+++ b/contrib/cross-arm-android-gnueabi.cmake
@@ -18,6 +18,22 @@ set(BUILD_SHARED_LIBS ON)
 set(CMAKE_C_COMPILER "${CROSS_PATH}/bin/arm-linux-androideabi-gcc")
 set(CMAKE_CXX_COMPILER "${CROSS_PATH}/bin/arm-linux-androideabi-g++")
 
+#
+# Different build system distros set release optimization level to different
+# things according to their local policy, eg, Fedora is -O2 and Ubuntu is -O3
+# here.  Actually the build system's local policy is completely unrelated to
+# our desire for cross-build release optimization policy for code built to run
+# on a completely different target than the build system itself.
+#
+# Since this goes last on the compiler commandline we have to override it to a
+# sane value for cross-build here.  Notice some gcc versions enable broken
+# optimizations with -O3.
+#
+if (CMAKE_BUILD_TYPE MATCHES RELEASE OR CMAKE_BUILD_TYPE MATCHES Release OR CMAKE_BUILD_TYPE MATCHES release)
+	set(CMAKE_C_FLAGS_RELEASE ${CMAKE_C_FLAGS_RELEASE}" -O2")
+	set(CMAKE_CXX_FLAGS_RELEASE ${CMAKE_CXX_FLAGS_RELEASE}" -O2")
+endif()
+
 # Where to look for the target environment. (More paths can be added here)
 set(CMAKE_FIND_ROOT_PATH "${CROSS_PATH}")
 
diff --git a/contrib/cross-arm-linux-gnueabihf.cmake b/contrib/cross-arm-linux-gnueabihf.cmake
index 12cf3e98d..c7ceae9d5 100644
--- a/contrib/cross-arm-linux-gnueabihf.cmake
+++ b/contrib/cross-arm-linux-gnueabihf.cmake
@@ -15,6 +15,22 @@ set(CMAKE_SYSTEM_NAME Linux)
 set(CMAKE_C_COMPILER "${CROSS_PATH}/bin/arm-linux-gnueabihf-gcc")
 set(CMAKE_CXX_COMPILER "${CROSS_PATH}/bin/arm-linux-gnueabihf-g++")
 
+#
+# Different build system distros set release optimization level to different
+# things according to their local policy, eg, Fedora is -O2 and Ubuntu is -O3
+# here.  Actually the build system's local policy is completely unrelated to
+# our desire for cross-build release optimization policy for code built to run
+# on a completely different target than the build system itself.
+#
+# Since this goes last on the compiler commandline we have to override it to a
+# sane value for cross-build here.  Notice some gcc versions enable broken
+# optimizations with -O3.
+#
+if (CMAKE_BUILD_TYPE MATCHES RELEASE OR CMAKE_BUILD_TYPE MATCHES Release OR CMAKE_BUILD_TYPE MATCHES release)
+	set(CMAKE_C_FLAGS_RELEASE ${CMAKE_C_FLAGS_RELEASE}" -O2")
+	set(CMAKE_CXX_FLAGS_RELEASE ${CMAKE_CXX_FLAGS_RELEASE}" -O2")
+endif()
+
 # Where to look for the target environment. (More paths can be added here)
 set(CMAKE_FIND_ROOT_PATH "${CROSS_PATH}")
 
diff --git a/contrib/cross-esp32.cmake b/contrib/cross-esp32.cmake
index 406763c61..b99c37d65 100644
--- a/contrib/cross-esp32.cmake
+++ b/contrib/cross-esp32.cmake
@@ -15,6 +15,22 @@ set(CMAKE_AR		"${CROSS_PATH}/bin/xtensa-esp32-elf-ar${EXECUTABLE_EXT}")
 set(CMAKE_RANLIB	"${CROSS_PATH}/bin/xtensa-esp32-elf-ranlib${EXECUTABLE_EXT}")
 set(CMAKE_LINKER	"${CROSS_PATH}/bin/xtensa-esp32-elf-ld${EXECUTABLE_EXT}")
 
+#
+# Different build system distros set release optimization level to different
+# things according to their local policy, eg, Fedora is -O2 and Ubuntu is -O3
+# here.  Actually the build system's local policy is completely unrelated to
+# our desire for cross-build release optimization policy for code built to run
+# on a completely different target than the build system itself.
+#
+# Since this goes last on the compiler commandline we have to override it to a
+# sane value for cross-build here.  Notice some gcc versions enable broken
+# optimizations with -O3.
+#
+if (CMAKE_BUILD_TYPE MATCHES RELEASE OR CMAKE_BUILD_TYPE MATCHES Release OR CMAKE_BUILD_TYPE MATCHES release)
+	set(CMAKE_C_FLAGS_RELEASE ${CMAKE_C_FLAGS_RELEASE}" -O2")
+	set(CMAKE_CXX_FLAGS_RELEASE ${CMAKE_CXX_FLAGS_RELEASE}" -O2")
+endif()
+
 SET(CMAKE_C_FLAGS "-nostdlib -Wall -Werror \
 	-I${BUILD_DIR_BASE}/include \
 	-I${IDF_PATH}/components/newlib/platform_include \
diff --git a/contrib/cross-ming.cmake b/contrib/cross-ming.cmake
index 94989f230..5d737dcfb 100644
--- a/contrib/cross-ming.cmake
+++ b/contrib/cross-ming.cmake
@@ -18,6 +18,22 @@ set(CMAKE_C_COMPILER "${CROSS_PATH}/x86_64-w64-mingw32-gcc")
 set(CMAKE_RC_COMPILER "${CROSS_PATH}/x86_64-w64-mingw32-windres")
 set(CMAKE_C_FLAGS "-Wno-error")
 
+#
+# Different build system distros set release optimization level to different
+# things according to their local policy, eg, Fedora is -O2 and Ubuntu is -O3
+# here.  Actually the build system's local policy is completely unrelated to
+# our desire for cross-build release optimization policy for code built to run
+# on a completely different target than the build system itself.
+#
+# Since this goes last on the compiler commandline we have to override it to a
+# sane value for cross-build here.  Notice some gcc versions enable broken
+# optimizations with -O3.
+#
+if (CMAKE_BUILD_TYPE MATCHES RELEASE OR CMAKE_BUILD_TYPE MATCHES Release OR CMAKE_BUILD_TYPE MATCHES release)
+	set(CMAKE_C_FLAGS_RELEASE ${CMAKE_C_FLAGS_RELEASE}" -O2")
+	set(CMAKE_CXX_FLAGS_RELEASE ${CMAKE_CXX_FLAGS_RELEASE}" -O2")
+endif()
+
 # Where to look for the target environment. (More paths can be added here)
 set(CMAKE_FIND_ROOT_PATH "${CROSS_PATH}")
 
diff --git a/contrib/cross-w32.cmake b/contrib/cross-w32.cmake
index 14cc234c3..0cb96cb3f 100644
--- a/contrib/cross-w32.cmake
+++ b/contrib/cross-w32.cmake
@@ -17,6 +17,22 @@ set(CMAKE_CXX_COMPILER "${CROSS_PATH}/bin/i686-w64-mingw32-g++")
 set(CMAKE_RC_COMPILER "${CROSS_PATH}/bin/i686-w64-mingw32-windres")
 set(CMAKE_C_FLAGS "-Wno-error")
 
+#
+# Different build system distros set release optimization level to different
+# things according to their local policy, eg, Fedora is -O2 and Ubuntu is -O3
+# here.  Actually the build system's local policy is completely unrelated to
+# our desire for cross-build release optimization policy for code built to run
+# on a completely different target than the build system itself.
+#
+# Since this goes last on the compiler commandline we have to override it to a
+# sane value for cross-build here.  Notice some gcc versions enable broken
+# optimizations with -O3.
+#
+if (CMAKE_BUILD_TYPE MATCHES RELEASE OR CMAKE_BUILD_TYPE MATCHES Release OR CMAKE_BUILD_TYPE MATCHES release)
+	set(CMAKE_C_FLAGS_RELEASE ${CMAKE_C_FLAGS_RELEASE}" -O2")
+	set(CMAKE_CXX_FLAGS_RELEASE ${CMAKE_CXX_FLAGS_RELEASE}" -O2")
+endif()
+
 # Where to look for the target environment. (More paths can be added here)
 set(CMAKE_FIND_ROOT_PATH "${CROSS_PATH}")
 
diff --git a/contrib/cross-w64.cmake b/contrib/cross-w64.cmake
index 2fc5de30d..9d4a45ab6 100644
--- a/contrib/cross-w64.cmake
+++ b/contrib/cross-w64.cmake
@@ -17,6 +17,22 @@ set(CMAKE_CXX_COMPILER "${CROSS_PATH}/bin/x86_64-w64-mingw32-g++")
 set(CMAKE_RC_COMPILER "${CROSS_PATH}/bin/x86_64-w64-mingw32-windres")
 set(CMAKE_C_FLAGS "-Wno-error")
 
+#
+# Different build system distros set release optimization level to different
+# things according to their local policy, eg, Fedora is -O2 and Ubuntu is -O3
+# here.  Actually the build system's local policy is completely unrelated to
+# our desire for cross-build release optimization policy for code built to run
+# on a completely different target than the build system itself.
+#
+# Since this goes last on the compiler commandline we have to override it to a
+# sane value for cross-build here.  Notice some gcc versions enable broken
+# optimizations with -O3.
+#
+if (CMAKE_BUILD_TYPE MATCHES RELEASE OR CMAKE_BUILD_TYPE MATCHES Release OR CMAKE_BUILD_TYPE MATCHES release)
+	set(CMAKE_C_FLAGS_RELEASE ${CMAKE_C_FLAGS_RELEASE}" -O2")
+	set(CMAKE_CXX_FLAGS_RELEASE ${CMAKE_CXX_FLAGS_RELEASE}" -O2")
+endif()
+
 # Where to look for the target environment. (More paths can be added here)
 set(CMAKE_FIND_ROOT_PATH "${CROSS_PATH}")