It's really annoying that the only smooth scrolling browser on the SP3 is IE. Firefox feels like it's running on a PC from the early 90s when I scroll.
Basically because Firefox sucks? It used to be a great browser 6 or so years ago. But ever since they moved on from 3.6 it became worse and worse.
I'm fine with IE, tbh. But if you're reluctant to use IE, you might wanna try Chrome. Definitely better than FF.