Would less tire pressure perhaps make more sense under these conditions?
Yes. I'm about your weight (225 pounds) and I find that the "fastest" tires are 700 x 28 or 700 x 32, inflated 100 to 110 psi. Narrower tires and/or higher pressures just slow me down.
On rough "chipseal" (a type of cheap paving common in the Western U.S.) roads, I also look for the areas where the chips have been smoothed out by car traffic. "Real" pavement (asphalt or whatever it's called where you are) is the best by far.
