I would like to know how you can do this in 20 sec!?
Well not sure you can do it in 20 exact but 23, maybe 22 should be possible.
Like so:
Start: keeping to the left platforms, single jump all the way to the main platform.
Walljump up the step.
Walljump directly onto the first jumppad.
When you get to the last jumppad make sure you walldodge onto the top of the next obstacle (not under it where the small rail goes)
Single jump the first couple of platforms, double jump the next.
Next gap you have to use the hammer - instead of using it to clear the gap use it to hammer jump onto the wall that you can use for wall dodging.
From there hammer jump into the finish.
Or you can
check this vid (24 time)
Not sure why I felt the need to do the last jump in reverse...