Replace the file with a 4 frames quickly.
http://tasvideos.org/userfiles/info/58093784426114001
In Submission #2712, Randil said:
Level 4 - 0 frames saved (17 in total)
The first section of the level can be quite laggy if you don't take care of the enemies as soon as possible. This is why I move back with Blue, in order to kill off enemies as soon as they appear. Because of this, it's not possible for me to climb up and take the rocket launcher around frame 17935. 3 rockets in total on this level, but Arc also pulls of an RPP here, so 2 frames saved using the RPP trick. I lose 2 frames by the between-levels frame rule, negating the 2 frames saved by the RPP.
I tried to change Level 4 and got this route - get two rocket launchers without any extra lag. This makes level 4 three frames faster. Influenced by frame rules, the final increase is 4 frames.