The Canon 85 1.2L II is a bit slow on Af, but don't get this lense wrong. Normally you're supposed to shoot models or persons acting in about 50 cm difference from for-/backwards. The lense has no problem to focus in an appropriate time in such short distances, it's just pumping if you loose the focuspoint and it starts to slide to infinity.
I never got any problems with the speed except of those minutes I tried to catch my small girl while running through the picture. But that's not a problem of the lense, it's a problem of me, chosing the wrong one
Getting the 100L 2.8 IS on the cam and the problem is solved (switched to 1.8m-infinity, only).
If you like to know why the 85mm 1.2L is slow you can see the chunk of glass right here:http://tinyurl.com/p7hr94v
[...] The inner lens is mounted on a ball bearing with 72 balls to keep it under its own weight[...]