diff --git a/CMakeLists.txt b/CMakeLists.txt
index 711f7fb3b..7445a32e1 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -18,7 +18,7 @@ set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++14 -Wno-unused-result -Wno-depre
 set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} -g -frtti -fexceptions")
 # enable for additional memory checking with fsanitize
 # set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} -g3 -fsanitize=address,undefined")
-set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} -O3 -frtti -fexceptions")
+set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} -O2 -frtti -fexceptions")
 
 if (${LINK_STATICALLY} MATCHES "true")
   set(Boost_USE_STATIC_LIBS ON)