Probably moot for most riders but if your at the pointy end of the time sheet lower pressure will generate heat quicker & easier as the tire flexes more. Exactly the same as on a track. I know quite a few riders who drop their tire pressures down to mid / high 20's (psi) for track days & pump them back up for the ride home. Thing is, you would need to get the heat into them immediately before you start your lap. They cool quickly.