The documentation says that the clipsToBounds property of UIView will clip the drawing to the bounds, or more precisely that the subview can't draw outside of the bounds of the superview.
Sounds nice, but what does that mean in practise? If I set that to YES, then my subview will automatically only draw those parts which are not outside the bounds of the superview, so it increases the overall performance? Or do I still have to make sure that I don't create any views that are not visible, i.e. inside a UIScrollView?