I wonder if there is a way to speed up scrolling to the speed that the page up / page down buttons scroll, with the smooth scrolling option turned on, but by pressing the up or down arrow, or clicking on the up or down scroll arrows with the mouse. The up/down arrows it is painfully slow scrolling and the mouse click over the up or down scroll arrows is even slower. This was one area that IE was quicker.
Don't know the answer to that one. I can say for sure, I had very bad scrolling issues like yours, mine were caused by not yet loading the drivers for my graphics card. I'm not saying that's your problem, but it may be something to look at.