In playing with Safari 5.1, I've found that it has lost the smooth scrolling effect. Scrolling with a scroll wheel is now choppy and unrefined. At first, this was mostly going to be a question about whether it's a bug anyone else has experienced, but based on more digging, I now suspect that it's also related to another change that Apple made to 5.1, as well as iTunes 10.4. These two apps are now geared toward touch-control input devices, with a non-linear response curve to mitigate the physical constraints of those types of devices, as well as input/response ratios that result in increments detrimental to most devices that don't belong to that category. And Apple, being Apple, does not provide a method to tune those compromises out. Sigh. Progress, I guess.