When I was experimenting with the clip in skull kid, I found that you can skip the part where you jump and the ceiling pushes you to the side and then you land and then jump again to start running on the JRB wall and instead when you do the jump where the ceiling pushed you to the side you can run onto the top of the JRB wall when you are at the peak of that jump. This trick is pretty hard but it probably save almost 2 seconds.

Here's a vid of me getting it -