I usually fill up at QT, and I've never experienced sluggishness--even when all 28 pumps are in use. Not all these pumps were in use. Only about half. I would estimate that I usually fill up in about 2-3 minutes.
I normally use QT because they're usually in good locations, they're clean, they have anything else I may need, there is plenty of room, the lots are clear of trash and things that may puncture tires, and the people are friendly. I'd never really thought about the speed of the pumping, until today.
Edit: I have felt the shutoff from the pump on the other side of the one I was using.