I was just looking at a long PDF file in preview and got off the computer for a bit. When I come back, the scrolling for some reason got extremely slow! I don't know what the heck happened. I have scrolling on the highest in system preferences and nothing helped. It takes very long just to get through a page. I know I could just use hyper scrolling, but it is still slow and only fast if I spin it all the way, which then goes all the way to the bottom of the page. What could be wrong?