Disable -O3.
Disable ccache and sccache.

Index: CMakeLists.txt
--- CMakeLists.txt.orig
+++ CMakeLists.txt
@@ -61,7 +61,7 @@ set(CMAKE_POSITION_INDEPENDENT_CODE ON)
 set(CMAKE_MACOSX_RPATH 1)
 set(CMAKE_MSVC_RUNTIME_LIBRARY "MultiThreaded$<$<CONFIG:Debug>:Debug>")
 
-if(NOT DEFINED CMAKE_C_COMPILER_LAUNCHER)
+if(FALSE)
     find_program(COMPILER_LAUNCHER NAMES ccache sccache)
     if(COMPILER_LAUNCHER)
         message(STATUS "Using ${COMPILER_LAUNCHER} as C compiler launcher")
@@ -71,7 +71,7 @@ if(NOT DEFINED CMAKE_C_COMPILER_LAUNCHER)
     endif()
 endif()
 
-if(NOT DEFINED CMAKE_CXX_COMPILER_LAUNCHER)
+if(FALSE)
     find_program(COMPILER_LAUNCHER NAMES ccache sccache)
     if(COMPILER_LAUNCHER)
         message(STATUS "Using ${COMPILER_LAUNCHER} as C++ compiler launcher")
@@ -662,7 +662,7 @@ if(NOT MSVC)
   set(CMAKE_CXX_FLAGS_DEBUG
       "${CMAKE_CXX_FLAGS_DEBUG} -g -O0 -DDEBUG -Wall ${M32_FLAG} ${CXX_EXTRA}")
   set(CMAKE_CXX_FLAGS_RELEASE
-      "${CMAKE_CXX_FLAGS_RELEASE} -O3 -DNDEBUG ${M32_FLAG} ${CXX_EXTRA}")
+      "${CMAKE_CXX_FLAGS_RELEASE} -DNDEBUG ${M32_FLAG} ${CXX_EXTRA}")
 
   if("${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang$" AND CMAKE_LTO)
     set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} -flto=${CMAKE_LTO}")
