Depending on your weight, I'd try a bigger tire, too. I weight 240, so your experience may differ, but I don't even think about anything skinner than 32 anymore, and most of my riding is on 35s.
For the record, I'm no slower on my 12-mile commute on 32s than I was on 23s, and the bike feels a LOT better. i suspect most if not all the difference is in the pressure, though. I have to run 23s at 105-110 or I pinch flat. The 35s feel fine at about 80psi.