Michael Angelo is AMAZINGLY fast, but his music sucks, but he beats Yngwie anyday... Yngwie is fast but not even close to the fastest. In fact, I know a senior in high school (he has attended all sorts of guitar clinics, playing with the likes of Vinnie Moore, John Petrucci, Steve Vai, Joe Satriani, etc.) who shreds faster and just as clean as Yngwie does...
Fastest sweep-pickers I've ever heard are probably Michael Angelo, maybe Rusty Cooley, and Jason Becker sweeps pretty damn fast, too.
For tremolo picking, John Petrucci or Paul Gilbert. Tony MacApline is fast at everything, too.
My personal FAVORITE shredder has got to be Jason Becker (he has Lou Gherig's Disease now, and he can't play, but if you haven't heard him, check out his album "Perpetual Burn"). He is a BRILLIANT musician, and not only could he play really really fast, he could right SWEET music, way better than Yngwie, and in multiple different styles (All Yngwie's songs and solos sound the same).