When working on large projects, the vertical scroll bar moves way too fast from bottom to top. The scroll bar handle needs to cover less area and move slower as the project gets bigger. I'm working on a 300 track project and the scroll bar jumps from track 1 to 300 in just a tiny movement on the scroll bar.
I don't understand what you mean by: 'but I don't want huge track previews to accomplish this.'
If the scroll bar icon has 1" of screen space to scroll 300 items, moving it 1/2" will move it to item 150. So, if you have a full screen available, you could say move the scroll bar 9" and still be be at item150, thus better control.