I disagree. Centipedes and other many-legged critters can move very fast. Every leg is just a tiny lightweight thing with its own balanced dynamics, just a part of a wheel basically. First thing that came to my mind is a plastic brush with flexible back. If you move a rollers along the back the bristles extend downwards and move backwards in a walking motion, just like a sea urchin does. Scale that and you have a walking machine moving amazingly fast. Tiny bristles yield and conform to any surface.