This game is relatively free of glitches but there are some pretty big sequence breaks. The reason there aren't any that save more than 30 seconds or so is because it's a 2D platformer which limits the possibilities for what you can skip. Check out the IL world records if you want to see them all.

The W1 levels (apart from 1-2 and 1-K) are a good place to start. Watch some runs of levels and choose the ones that look manageable. Would definitely avoid RNG bosses for now.

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Bonk

This has been discussed before in the Four Medals% thread, but since then Leah decided to do just this, completing the run in 10:05:59. There is no recording of this, and she stated it was the worst run she's ever decided to do, so we might never see a recorded run of the category. Also, the run had a 20-minute break after puzzle pieces, so sub 10 was barely missed.

That might finally explain The Completionist's 1:47 in 2-3 if he knew about DA from Pack's comp. It also makes me wonder if the fast loads you get on emulator are the reason for this, which might also provide a reason why DA times vary on console (Wii and Wii U loads aren't consistent)