iOS 5 released web designers a new property -webkit-overflow-scrolling:touch
that uses the iOS devices hardware accelerator to provide native scrolling for a sc
I also experienced the problem where overflow scroll with -webkit-overlfow-scrolling set to touch resulted in redraw problems with positioned elements. In my case I had a list where the individual items had relative positioning so that I could use positioning on their child elements. With the above CSS on iOS 5, when the user scrolled hidden content into view, there was a momentary delay before it redrew the screen to review the elements. It was really annoying. Fortunately I discover that if I gave the parent node position relative as well, this was resolved.