honestly pac's speed is way overrated. Most of his flurries are just arm punches, not fully extending and using his hips.
Tarver, Hopkins and Vitali don't have average handspeed at all. Vitali is one of the fastest handed big men of all time. Tarver was almost as fast as Roy Jones in the fight fight and Hopkins in his prime was able to keep up with Roy Jones as well.
Hagler and especially Hopkins had better-than-average handspeed. Hopkins's speed and athleticism get underrated. He doesn't solely rely on brains and old-school technique, he does have some quickness to back it up. Oh that reminds me, Pavlik's speed is pretty average.
Trying to think of some not already mentioned, the body snatcher? Chavez? often went up against faster fighters than them like. Valuev for the lulz.
Morales, Barrera, Marquez (both bro's), Sanchez, Lopez, Canto, Olivares, Salido, Montiel, and Chavez all have/had above average handspeed....Especially Sanchez, Lopez, Canto, and Montiel...come on, man..