I have an Excalibur Exomax that'll fling a bolt at 350 fps. The fastest crossbow on the Excalibur site is the Excalibur Matrix 380 Xtra at 380 fps. The PSE Tac Elite seems to be the one that most people identify with as one of the fastest crossbows and they advertise speeds between 405 - 395 fps.
I think that would be a pretty good comparison starting point.
