Ignore the rerecord numbers, will be updated later.
For newbies:
Jump height is fixed.
You can ignore "being hit" standing animation by pressing A (jump), going forward without wasting a single frame.
You can cancel your fire to avoid being slowdown by ducking for 1 frame after shooting, or firing before falling down.
Comparison with resynced version of that run:
13 frames faster start by resetting 7-8 frames after power on to press start earlier.
The game sucks, so you need to manipulate the timing of pressing select (for selecting hard difficulty) and starting the game/cutscenes to decrease the loading time for resources. Something 12 frames can be achieved with this.
~31 frames faster by optimal movement and maximizing speed to reach cam X positions to load next platform objects.
~1100 frames faster boss fight by hitting the boss once his invulnerability wears off. Since we visited that random guy in that door, we deal 2 dmg with bigger hitbox. Without this power, we could only dmg him (1 per hit!) down to 6 health, costing more time to wait for it to also reappear and kill the remaning (6) hits.
Cutscene loading time manipulations in progress.
Other tricks not mentioned:
Jump has fixed height, however jumping at specific frames can change the cam Y speed, letting you hit a platform earlier.
It's better to jump over the edge of a platform to avoid nullifying your X speed. Obviously scenario dependent, when you want to jump earlier or just move forward to win.