Just came across something with the scrolling, are you sure it's desired behavior? If I split the view in half horizontally, the fast scrolling works just fine. If I unsplit the view or make the other view as small as possible it goes back to jumping. It seems it just has trouble rendering everything in the single view and doesn't have anything to do with the scrolling because although the view is smaller it's still scrolling the same amount of lines.
EDIT: I think I've tied the jumping on my end to my
theme. I have a background color set for comments and it seems to be the cause. If I remove all comments that span more than a few lines or change themes it stops jumping. Might this be related to the
font rendering bug I reported a little while back? Seemingly caused by the background color being set for comments as well.