I've noticed that most, if not all, of the faster runners I know have a very distinct form. Even when running slow their feet continue through with motion after the foot strike and come up and almost touch their butts. In other words, even when they are running an easy pace they are not shuffling. One would think this extra motion is not necessary but when you watch them run it looks amazingly smooth and efficient.
My motion is the complete opposite. Even at faster paces my feet do not continue very far after the foot strike. Is this something worth studying and working on?