In my many decades of commuting, I have not found average speeds to vary significantly no matter what bike I ride (from 50+ pound loaded commuting bike, to 20 lb single speed). Tires, road surface, traffic, intersections all have more effect than bike. My recommendation is to ride the new bike for a few months before you start to make changes. Once you become familiar with it's function and performance, you will be in a better place to make good decisions.