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

Index: CMakeLists.txt
--- CMakeLists.txt.orig
+++ CMakeLists.txt
@@ -191,7 +191,7 @@ elseif((CMAKE_BUILD_TYPE STREQUAL "Release") OR (CMAKE
   elseif(MSVC)
     set(WL_OPTIMIZE_FLAGS "/O2")
   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.")
@@ -559,15 +559,6 @@ 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(OPTION_BUILD_TRANSLATIONS)
