Index: src/CMakeLists.txt
--- src/CMakeLists.txt.orig
+++ src/CMakeLists.txt
@@ -355,7 +355,7 @@ endif()
 # Note that find_library does not reliably find it so we have to resort to this.
 # Also, passing -latomic is not always the same as adding atomic to the library list.
 include(CheckCSourceCompiles)
-if(NOT CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
+if(NOT CMAKE_CXX_COMPILER_ID STREQUAL "MSVC" AND NOT AVOID_LINKING_ATOMIC)
 	set(CMAKE_REQUIRED_LIBRARIES "-latomic")
 	check_c_source_compiles("int main(){}" HAVE_LINK_ATOMIC)
 	set(CMAKE_REQUIRED_LIBRARIES "")
@@ -965,7 +965,7 @@ else()
 		endif()
 	endif()
 
-	set(CMAKE_CXX_FLAGS_RELEASE "-DNDEBUG ${RELEASE_WARNING_FLAGS} ${OTHER_FLAGS} -pipe -funroll-loops -O3 -fomit-frame-pointer")
+	set(CMAKE_CXX_FLAGS_RELEASE "-DNDEBUG ${RELEASE_WARNING_FLAGS} ${OTHER_FLAGS} -funroll-loops -fomit-frame-pointer")
 	if(CMAKE_SYSTEM_NAME STREQUAL "Linux"
 			AND CMAKE_CXX_COMPILER_ID STREQUAL "Clang"
 			AND CMAKE_CXX_COMPILER_VERSION MATCHES "^9\\.")
