Good design is maintaining your loopbacks in OSPF (so you only have /32's for each router in your OSPF scope) and then build iBGP sessions between your routers to actaully do the real brunt of the work.
It all depends what you mean with the word "fast". If you mean fast routing calculation, I think BGP4 is one of the fasted if you're working with more then 1 milion routes. If you need fast convergence, BGP is not so fast. OSPF provide faster convergence.
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