One of the biggest power drains with better players is using a knock-kneed stance (left). They kick their knees in to be more stable at address, but this stance actually makes it easier to sway and slide during the swing.
Maximize power by bowing your knees like you would riding a horse. This adjustment will engage the glute muscles in your rear end that are essential to stabilizing your body as you pivot back and through. Those muscles are often overlooked as a power source. With your knees bowed out (below), practice swinging your driver at full speed. You'll feel your glutes activate and stabilize your body as you go. A stable body creates a platform for turning on the speed.