In my 6:10 speedrun I completely on accident stumbled on some weird bug or glitch,where if you select"Quit to Title"in the"SUPER"room after you've gotten all 5 letters,then select a new save and go through the whole game,the letters will already be filled in when you get to that room. I'm not sure if this is against the rules for this game,but it's a pretty neat timesaver,I'd guess around 15-20 seconds
These tricks were originally found by finath and were originally console-only to my knowledge, but I did some tinkering and managed to find a method for PC,the tricks are just done a little differently These tricks save a TON of time in 100%,I'm not sure just how much it saves,but I'd say around 10-11 minutes
First trick: Hitbox glitch into the corner,jump out of bounds,hit either crouch then immediately hit backwards(or maybe the other way around I'm not sure),hit pause and wait until the environment loads in
2nd trick: Do a doorride off the door and (without going too far off the wall or the rubble)walk around the rubble,crouch to get through the doorway,then like the end of the Any% trick crouch and walk on the roof until you get pushed back inbounds,open/close the doors like in the video to be able to backtrack and get the 3 collectibles,then go through the doorway at the end of the hall