Someone mentioned earlier the misconception that higher pressure = higher speeds. The basic idea is that you get a larger tire/road contact surface area as opposed to jumping and/or skipping on the road surface.

There was also a link posted to an article about 25mm tires being a bit faster than 23mm. Maybe you're already using the 25's, but thought I'd mention it. Might get the best of both worlds with 25mm: more comfortable and slightly faster (for us mere mortals at least).