My impression of the challenges:
Speed: Some of the times are just crazy... probably the hardest one
Warps: Go through it once, make sure you learn the level, know what you have to warp to and such, and take your time, there's no rush with this one
Steps:Use warps for everything. Need to move about 2 feet to grab that cube? Warp 2 feet. Basically, only walk when completely necessary.
I think speed is the hardest one, by far
THE JACKEL