I think we can make the speed run of this game shorter using glitches that haven't quite been explored yet. I will make this thread in order to start a good discussion on it. I drop a glitch I found below.
I found a way to glitch into the wall and warped right up to the key door in the cheese wheel room in 2-4. I used the wheel to clip into the wall and zip up to the area with the door. I forget how I got it to clip into the wall, but I have several videos on my YouTube of it so if anyone can learn how to do that consistently we can save some time on 2-4. I don't know if there are other items you can do this with yet, but I do know that corners are really glitchy. Here is a video. Hope you mute it because I sound stupid.
Here is another glitch having to do with the wheel, don't know if they are connected.