I appreciate your lived experience, but at the same time the rest of us will seek answers in basic physics concepts, none of which help explain such phenomenon. Is it possible you just got stronger or subconsciously tried harder because you wanted the heavy bike to be faster? Did you add weight but also make sure your bike was well tuned? Tire pressure and a greased chain go a long way. I certainly agree that the weight weenies can go way overboard though.