Here are the fastest players I have ever seen and heard:

Rusty Cooley - most technically difficult runs at incredible speed, ridiculously fast alternate picking and sweep picking
Francesco Fareri - sounds like a Nintendo game on steroids - horrible music but unbelievable speed (possibly the fastest player of the lot)
Mathew Mills - the fastest most ludicrous sweep picker out there, so fast that he looses musicality
Michael Angelo Battio - the craziest string skipper ever, brilliant sweep picking technique too
Yngwie Malmsteen - when it comes to neoclassical he is the man, brilliant at everything but never changes his direction
Michael Romeo - when it comes to double multiple finger tapping, sweep tapping and economy picking this guy is the cream of the crop
Sean Lane - crazy fast at everything!

There's loads of urban legends about Marcus Paus hitting 48 notes per second, listen to the track and you will realise that it is sped up. The tuning is way above normal pitch, the high notes come in around the 30th fret. If he was indeed using a 33 fret guitar like an LGM Leviathon it would be even more publicised because it is virtually impossible to shred over those frets without pick tapping because they are so thin.

Check each of these guys out on youtube, they are all insane - some easier on the ear than others but all the fastest I have ever seen