My AF experience with the F 70-210 (I have the SMC version with red lettering) has been that it's deceptive-- the hand-feel made me
think it was a slow focuser, but after using it for a while, especially to shoot events, I realize that it actually focuses fast. Fast enough to track people running on the far side of a hockey rink, for instance (with AF-C).
Maybe the heavy jerking and thudding* when it's focusing makes us subconsciously perceive it as slower than it really is?
*like a sledgehammer coming to a stop, oh yeah