I like to think I play fast. My son and I occaisionally play our home course over lunch and get in 9 holes and I am back in an hour and a half including drive time (10 min each way) if the course is empty.
My ex and I played Royal Melbourne three times in two days and never took more than 2H 45M, with me shooting 80 something and her shooting 120 something. One time, we were behind a ladies league and they didn't hold us up. (Both events mentioned to dispel the myth that average female players are the main problem in slow play - we have seen the enemy and the enemy is us!)
The RM experience taught me (I think) that distance from green to tee is one key design wise, as are wide playing corridors.
From the play side, I try not to wait until my partner has played to plan my shot, pick a club, etc. Perhaps I am anti social that way (and have occaisionally tossed out a gratuitous "nice shot" after a cold top because I really wasn't looking) but I think waiting for others to play is the main culprit, and if sharing a cart, its a double culprit to wait rather than drop off your partner and go to your ball (safety permitting)
I also eliminated practice swings years ago as well as looking at the putt from the other side of the hole (in most cases) In truth, I can only recall a few occaisions where that second look helped me make a putt. Oh, and I play ready golf, damning the customary order of play. (perhaps because of that "shoot the first guy on the tee" story I have told hear, I should be a little more selective on that one)