===================================================================
Index: Aegisub-524c6114a82157b143567240884de3a6d030b091/configure.ac
===================================================================
--- Aegisub-524c6114a82157b143567240884de3a6d030b091.orig/configure.ac	2019-03-29 13:17:21.692386078 +0200
+++ Aegisub-524c6114a82157b143567240884de3a6d030b091/configure.ac	2019-03-29 13:17:38.925081533 +0200
@@ -145,8 +145,8 @@ AS_IF([test x$enable_compiler_flags != x
     CFLAGS="$CFLAGS -O0"
     CXXFLAGS="$CXXFLAGS -O0"
   ], [
-    CFLAGS="$CFLAGS -O3"
-    CXXFLAGS="$CXXFLAGS -O3"
+    CFLAGS="$CFLAGS"
+    CXXFLAGS="$CXXFLAGS"
   ])
 ])