- Don't set -O3.
- Don't install source docs.
- Don't use ccache.

Index: CMakeLists.txt
--- CMakeLists.txt.orig
+++ CMakeLists.txt
@@ -80,7 +80,6 @@ wl_set_if_unset(WL_INSTALL_DATADIR "./data")
 wl_set_if_unset(WL_INSTALL_BINDIR "${CMAKE_INSTALL_PREFIX}/games")
 
 if(NOT CMAKE_C_COMPILER_LAUNCHER)
-  find_program(CCACHE_PROGRAM ccache)
   if(CCACHE_PROGRAM)
     set(CMAKE_C_COMPILER_LAUNCHER ${CCACHE_PROGRAM} CACHE STRING "C Compiler Launcher" FORCE)
     set(CMAKE_CXX_COMPILER_LAUNCHER ${CCACHE_PROGRAM} CACHE STRING "CXX Compiler Launcher" FORCE)
@@ -204,7 +203,7 @@ elseif((CMAKE_BUILD_TYPE STREQUAL "Release") OR (CMAKE
       set(WL_OPTIMIZE_FLAGS "/Ob2")
     endif()
   else()
-    set(WL_OPTIMIZE_FLAGS "-O3")
+    set(WL_OPTIMIZE_FLAGS "-O2")
   endif()
   if(("${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU") AND (CMAKE_CXX_COMPILER_VERSION VERSION_LESS 7.6))
     message(WARNING "GCC <7.6.0 is known to cause segfaults in release builds. Please consider upgrading to GCC version 7.6 or newer or using Clang. Adding selected overrides to suppress reporting of known bugs.")
@@ -591,15 +590,6 @@ install(
   DESTINATION ${WL_INSTALL_BASEDIR}
   CONFIGURATIONS Debug;Release;RelWithDebInfo;None
   COMPONENT CoreLicenseFiles
-)
-
-install(
-  DIRECTORY
-    doc
-  DESTINATION ${WL_INSTALL_BASEDIR}
-  CONFIGURATIONS Debug
-  COMPONENT DocFiles
-  PATTERN "CMakeLists.txt" EXCLUDE
 )
 
 if (UNIX AND NOT APPLE)
