I go top speed when bobbin winding, that's it. Otherwise I'd estimate I'm at half to three quarter speed, or slower if I feel it's required.
I did once have a complaint that I was irritating someone else (a quilter) in the room by sewing too slowly. I wasn't going particularly slowly, and wasn't going at a noticeably different speed from others in the room, but for some reason I was picked out to be complained about. I've always thought that was odd, and said so at the time, lol.