diff --git a/CMakeLists.txt b/CMakeLists.txt
index 89ca2ce..10e693e 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -28,9 +28,9 @@ set(CMAKE_BUILD_TYPE "Release")
 # option 2 (works but not preferred): uncomment one of the following two lines then run/rerun cmake:
 
 # -O3 is full optimization in gcc/g++
-#set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} -O3")
+set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} -O3")
 # -O0 is no optimization in gcc/g++
-set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} -O0")
+#set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} -O0")
 
 
 #