The Performance Ultras are supposed to be designed for hot weather, better wicking capabilities. I have them but havent' worn them yet. The inseam is a little shorter than what I am used to but the chamois feels heavenly (for the brief time i tried them on). I love my Performance Elites, have done a century and lots of miles in them. I am looking at the Terry Bellas next to see what they are like. I think they will be my next purchase.