If you are year round on the asphalt with the pugs might I suggest a set of Black Floyd's for the summer and switch to Nates or Larry's for the winter. OR with the pugs you can throw a set of 29er wheels on it and run slicks.

Yeah I know, you are not made of money. Just a suggestion.

and to answer your original question. Seem logical that less tread ought to speed you up. What pressure's are you running?