I generally don't worry too much about static vs dynamic dispatch. Not that I use a lot of interfaces all over the place, but there are certain places where I do (for instance persistence layer abstraction - where it doesn't actually matter since any overhead caused by that is many orders of magnitude smaller than the cost of what the call does anyway)

Also, if someone can understand the code, they can optimize it if needed. So in a way, trying to express oneself clearly and simply can be a way to help optimization later.