New WIP, fully resynched up to Death Egg 1.
After the previous improvement, I also optimized the capsule hit on Hydrocity 2. This caused desynchs -- guess which levels?
Yeah. marble Garden 2 desynched; resynching led to no loss or gain. Then Carnival Night 2 desynched (I hate those balloons). On the flip side, I managed to get Tails slightly earlier, leading to an improvement of 3 frames (final time: 0:41::41).
Launch Base 1 desynched because the level-swap lag frame at the score tally happened 1 frame later than the previous WIP. That was easily fixed, but still it cost me a frame in real time. There was an extra lag frame at the start of a level, but I haven't paid attention which one.
Mushroom Hill 1 desynched at the mini-boss -- Tails got hit 1 frame later, the reverse of what happened earlier. I replayed the fight so as to prevent this from happening again (Tails goes head on into the flame now), and this led to an improvement of 11 frames, down to 0:32::50. With some subpixel manipulation, I managed to resynch Mushroom Hill 2 without needing to replay it.
Then the Lava Reef 1 mini-boss desynched because it was further right (by 10 pixels). After resynching it, Sky Sanctuary desynched at Mecha Sonic. I added a small (1 frame) pause to manipulate luck, as the pattern was the slowest.
Then the Death Egg 1 mini-boss desynched. I replayed it, and ended up gaining 1 frame in the fight -- so the level is down to 1:04::03.
All told, this is 132 frames of improvement from the previous WIP up to this point. I am, of course, comfortably sub-30 min now.