I did some more comparisons with that lava segment, and here's what I get: I am fifteen frames slower when falling down to the platform just before jumping with the lava, but I have a bit more velocity because of different jumping, I think. This causes me to gain back 11 of those 15 frames by the time we both hit the next wall. So, if the original lava bounce works, it should save at most four frames. I could be wrong on this, so if anyone else wants to compare, feel free.
Four frames or not, the original way still looks cooler, so I dove into some Marble Zone 1 lava fun for a while, but still no success at this point. I got bored with that for now and did Marble Zone 2.
The WIP is here. I'm not saying Marble Zone 1 will stay the way it is; I have no problem redoing levels, and I've gotten pretty good with a hex editor since Super Demo World, so redoing may not even be necessary as much as cut-and-paste.
Marble Zone 2 Xebra -4.01 JXQ Diff
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First jump 3.37.52 3.33.51 3.31.09 2.42
1st switch 3.42.49 3.38.48 3.35.56 2.52
Past lava 3.46.56 3.42.57 3.40.03 2.54
Done pushing 3.50.51 3.46.50 3.44.00 2.50
Push right 3.53.54 3.49.53 3.47.03 2.50
Edge before swings 3.57.23 3.53.22 3.50.33 2.49
On platform (all) 4.00.13 3.57.12 3.53.28 2.44
2nd switch 4.02.05 3.58.04 3.55.19 2.45
Break block 4.16.24 4.12.23 4.09.38 2.45
Land on lava block 4.21.54 4.17.53 4.15.00 2.53
Highest step 4.24.20 4.20.19 4.17.30 2.49
End 4.31.58 4.27.57 4.24.54 3.03
I gain some frames in the beginning, but lose them in the area with the swinging platforms because they were positioned differently and I had to slow down a bit (which I did by jumping lower). I gained 21 frames in the last segment of the level. I'm not positive where, but I think that avoiding hitting the spiked-worm enemy near the end helped. I also tried waiting on the last spiked chandelier to jump directly to the top grass, which worked, but was slower.
The area after the second switch has some real rapid-looking jumping. I did this because in some cases, holding the jump button longer keeps your speed just slightly faster, and that gained me a frame here or there. Finish time is still 0:53.
