There are two sets of "knobs" on the bottom of each foot. One set is smooth (low friction) and the other have rubber/vinyl on them (high friction). I found that the rubber ones can get a bit dirty and slip. Just rubbing a pencil eraser on the rubber ones seems to improve the traction, and hence the speed, a bit.
I also found that using the second gait option the V2 moves pretty quickly on our wooden floor.