diff --git a/src/Makefile b/src/Makefile
index 4b993c881..034a2230f 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -66,7 +66,7 @@ ifndef BUILD_ID
 endif
 $(info BUILD_ID: $(BUILD_ID))
 
-CFLAGS += -MMD -MP -O0 -g -I common \
+CFLAGS += -MMD -MP -O3 -I common \
           -Wall -Wextra -Wno-char-subscripts $(USER_CFLAGS) \
           -DCA65_INC="\"$(CA65_INC)\"" -DCC65_INC="\"$(CC65_INC)\"" -DCL65_TGT="\"$(CL65_TGT)\"" \
           -DLD65_LIB="\"$(LD65_LIB)\"" -DLD65_OBJ="\"$(LD65_OBJ)\"" -DLD65_CFG="\"$(LD65_CFG)\"" \