It generally seems that "fast" kills are tied to tissue damage, which is a function of speed and bullet size/design. Maybe you got a hard batch of Hornady bullets?
I don't shoot my .35cal bullets much faster, as I download my single shot Whelen to .358win speeds (225 Accubond at 2,420fps). Deer and hogs do run sometimes, but I've had good results on damage to vitals and blood trails. Shots have been from 100 to 225 yards and I don't think any animal ran more than 40 yards.
