Ditto what Maxpower220 said. Getting the right polisher and pad can make a HUGE difference. I work near the polishing and finishing group and they use nothing larger than 3" pads on good quality industrial polishers. They use three (or more) different pads. One is a "heavy" cut, one is "medium" and one is a polishing pad.
Here is a video that we pass around at work because the guy knows his stuff.