... I'm sure there's still some difference but I bet the softness makes them feel slower than they actually are.
This.
When riding on narrow, high pressure tires, there is a definite high-frequency vibration, or buzz, as the tires bounce along the road imperfections. Wider, more supple tires don't bounce, they roll, and they do it with less resistance. However, the missing buzz makes them "feel" slower.