No, I don't think you are doing it backwards for speed events. I was thinking of dressage where the movements need to be precise. You're right, in barrel racing you sure don't want something to slow them down. What do you think about those weirdo contraptions that you see people use occasionally, like an easy stop? The stuff that looks like torture devices. I'd really have to hate the horse before I'd use some of that stuff. (and I've had a couple that I hated that bad!)
I'd say if you have to use something like that, you don't need the horse, or the horse isn't a barrel horse.
Becky