grayrest

Rolling resistance is basically dependent on tire construction and not so much on the width. Here's a Bicycle Rolling Resistance comparison of the range of GP5ks. The difference between a pair of 23mm at 100 psi and 32mm at 60 psi is under 5 watts and 200 grams or so. There's going to be an aero loss as well due to the width but unless you're in competition and pushing the limits for every watt there isn't a lot of performance difference.

Jan Heine says width doesn't matter much at all and runs/sells really wide road tires but I find his testing less controlled than BRR. What I do like about his writing is that it got me to understand that tires aren't fast just because I can feel the road buzz so I drop the pressure on all my tires way down because I enjoy it.