Level 5, 146 frames faster. It can be 155, but I lost 9 frames cause I wanted to hit the enemies after the boss, causing lag. Not sure if I want to keep it this way or not.
Okay, finally done with level 4 (I think, never know). Saved an additional 253 frames over the last version I posted. Thanks to Tompa for making me aware of spike slide boosting!
Finished the game, there are some sloppy moments for this test run, including a couple missed shots on the final boss that would be fixed if I ever did a final version.