Avoid forcing -O3 and let users set these as wanted.
--- a/libretro/Makefile
+++ b/libretro/Makefile
@@ -578,8 +578,8 @@ ifneq (,$(findstring msvc,$(platform)))
    CFLAGS += -O2 -DNDEBUG
    CXXFLAGS += -O2 -DNDEBUG
 else
-   CFLAGS += -O3 -DNDEBUG
-   CXXFLAGS += -O3 -DNDEBUG
+   CFLAGS += -DNDEBUG
+   CXXFLAGS += -DNDEBUG
 endif
 
    ifneq (,$(findstring msvc,$(platform)))
--- a/unix/configure.ac
+++ b/unix/configure.ac
@@ -64,11 +64,6 @@ AC_ARG_ENABLE([debug],
 if test "x$enable_debug" = "xyes"; then
 	AC_S9X_COMPILER_FLAG([-g],  [g])
 	AC_S9X_COMPILER_FLAG([-O0], [o0])
-else
-	AC_S9X_COMPILER_FLAG([-O3], [o3], [
-		AC_S9X_COMPILER_FLAG([-O2], [o2], [
-			AC_S9X_COMPILER_FLAG([-O1], [o1])])])
-	AC_S9X_COMPILER_FLAG([-fomit-frame-pointer], [omit_frame_pointer])
 fi
 
 AC_ARG_ENABLE([mtune],