So I made two videos that are meant to be as comprehensive as possible about speedrunning the game (at least the any % and all weapon categories).

The first video is mostly about basic stuff about the game and exist more for completeness sake but it also include an explanation about the two main glitches of the game which start at 15:47 and is available here :

The second video is a breakdown of the routes for the individual level in the any % and all weapons category, again timecodes are available in the description if you only care about specific levels. It is available there :

I hope this will help anyone wanting to learn to speedrun the game, at least it'll make for a good way to compile knowledge instead of having it spread out through old forum threads. Good luck and have fun =)