diff --git a/configure.ac b/configure.ac
index ad3c4687f8c686d34aa0523801a0cfca44a198cf..9d72238c1f75c9eded9534823dd1d3e1ffb28d19 100644
--- a/configure.ac
+++ b/configure.ac
@@ -639,7 +639,7 @@ AC_ARG_ENABLE([debug], AS_HELP_STRING([--enable-debug], [Build in debug mode, ad
 
 AS_IF([test "x$enable_debug" = "xyes"],
       [CXXFLAGS="${CXXFLAGS} -g -fno-omit-frame-pointer -Wall -Wextra -Wnon-virtual-dtor -Wno-unknown-pragmas -Wformat=2 -O0"],
-      [CXXFLAGS="${CXXFLAGS} -DNDEBUG=1"])
+      [CXXFLAGS="${CXXFLAGS} -DNDEBUG=1 -O3"])
 
 dnl What Makefiles to generate
 
diff --git a/contrib/src/main.mak b/contrib/src/main.mak
index 11f9c330522cb19843cb9c368f0ac77aef23ccbb..47256305f2e7d5f2b6e31ebc4cd31274c0437614 100644
--- a/contrib/src/main.mak
+++ b/contrib/src/main.mak
@@ -198,9 +198,9 @@ endif
 EXTRA_CXXFLAGS += -std=c++14
 
 ifdef ENABLE_DEBUG
-EXTRA_CFLAGS += -g -fno-omit-frame-pointer
+EXTRA_COMMON += -g -fno-omit-frame-pointer
 else
-EXTRA_CFLAGS += -DNDEBUG=1
+EXTRA_COMMON += -DNDEBUG=1 -O3
 endif
 
 cppcheck = $(shell $(CC) $(CFLAGS) -E -dM - < /dev/null | grep -E $(1))