the friction and heat of both....if you get em that hot often look into some fender fins for cooling.still have too much heat,then I would go w/slotted olny and pads the maker recommends.drilled wont last as long on the street,might crack over time.your wheels might also be restricting airflow to them....mostly I mean hubcaps.take em off if you have em.
improving your airflow is key regardless of your choice,it will show improvements regardless of type of rotors/pads