I found a strategy in level 9, it saves around 0.8 seconds. You need to place a bed at the corner of block next to left chest (you can only place it on the last pixel of block, or flame will kill you). After this you need to jump instantly after reaching land (frame perfect), get hit by a wall, jump through the flame and complete the level with my another strategy (you can read about it in Sandstorm187's epic guide). Here's the link to my TAS level 9 completition with this strat:

gonna do this in runs kappa

Unless you have the trick mastered, its pretty risky to do it runs. Just to save about a second, its not worth it. And the setup itself can take about 2 seconds from the start of the level. Overall this trick is probably an IL - only , unless people get really good at it.

(Note: I saw your "emote" - apparently the kappa emote doesn't work anymore :(

1. I actually will do this in runs unless it proves too difficult, but it seems to be very similar to the 8 shortcut, which is consistent
2. The TAS strat requires you to move you mouse much less, so in the context of a full-game run, this would save 1-4 seconds
3. Kappa LUL don't work but KEKW does for some reason