The idea is to group items (not Group, just the base items) into 3 proxy object (one for above, one for current and one for below view) and only move the proxy once when sliding the scrollbar around. When the items are stopping moving, or move to fast (If the cost of double rendering is not offsetted by having to render more than twice, looking at the speed vector should help make that decision) and they start to be animated, we should get them out of the proxy so that local animation don't trigger massive redraw. This require work in cooperation with the position manager.