The two tricks that are most versatile and useful are the pause jump and the bread boost (as I have dubbed them).
Lets first start with the pause jump.
It's surprisingly simple, just pause, press jump at least twice, then unpause while still holding the jump button.
The second trick is the bread boost, a trick to achieve roughly the same effect as a pause jump. (It functions no matter which direction you face).
This trick is also simple, while in air (not falling too fast), and next to a wall, throw bread toward the wall and jump and hold jump at roughly the same time.
Recently some new mods have been made by GoldZook for this game. As these mods make it significantly more convenient to do IL speedruns with easier resetting thanks to a teleport mod (which also makes practicing levels way easier!), and also basically all speedruns in general with an in-game timer m