In my experience (which is extensive but doesn't include carbon), tire size and pressure make more difference than frame material. I weigh about 20 pounds more than you do, and I do all my riding these days on 32mm or larger tires. I've done the same 25-mile RT commute for almost 30 years, 100 or more times a year, and there's no correlation between tire size and my times, whether I'm using 23mm or 41mm. Even if, say, 35s were a little slower, I'd ride them anyway. I'm only going to work...