I haven't tried with other Snes9X versions, I'll test it for the syncing issues and see.
By the stage 2 pre-boss room, you mean the second part of Act 2? Frame-wise, that area can't be completed any faster (Same goes with every other area in the game, except a couple of bosses due to getting bad random attack patterns). The player doesn't lose speed at all if attacking while jumping, and properly doing the "keep run speed" jump.
Slowdown-wise might be a completely different story though, due to the heavy special weapon use. I should have considered that, but I was thinking "using weapons" offered more to watch than just running and jumping.
But after starting a run on the JP version (soon to delete that and start over again, yay for poor special weapons planning), I'm actually not as happy with this US version run either.
And that is interesting, the censorship differences between the versions. I also noticed the JP version text between levels increases in hilarity as the game goes on, reaching 'Zero Wing' level at the end.
And a realization... Frame-wise, the JP version run is currently 100 frames less than the US version (comparing at the start of the Act 4 Boss fight).
Considering special weapons are useless against the last 2 bosses, I'm thinking this US version run will definitely be obsoleted by any JP version run.
I've come to my senses, and will cancel this one. I just wasn't sure at first about the 'US version only' thing, after seeing that one JP-version Link's Awakening run get rejected.