I found two possible time saves, one which I cannot replicate but I haven't tried much yet. Not sure if you guys have encountered these, but I haven't seen them in any runs.

1. In the first building in level three, you usually stop at a certain spot very briefly to make the robot guy fall through. I found that if you jump at the corner/ledge (before the spot where you would normally stop walking briefly) and graze your head on the ceiling, the robot drops down every time. It feels like it is a little quicker sometimes, and definitely easier to do for me.

2. In the swimming section of the dam towards the end when you are dropping down and the path splits into two and the bomb is on the right, you usually cannot avoid touching the top of it and initiating the slow dropdown to the center of the bomb. I somehow avoided touching it and dropped down past it without even diffusing because I expected it to automatically do its thing like it normally does. If this can be replicated, it would save a second or so if you can initiate the diffusing at the center of the bomb like we do with all the other ones.

For the swimming section, it appears that this takes a very similar amount of time to do it the normal way by just engaging in the bomb diffusion from the top. I believe it takes the same amount of time to fall naturally as it does to fall during bomb diffusion.

Nice, I have tried a few different things for that falling guy. I have seen the swimming thing before, but could never really get in there without touching the bomb at the top.