[84LX89GT]

As mentioned the higher the octane you run the more timing you need to burn it. Higher octanes are slower burning but when you advance your timing it burns longer leading to a more complete burn. With correct timing there are less byproducts and more power available. If you don't advance your timing it won't burn as completely and will leave gas in the cylinders that will help wash down the cylinders, dilute the oil and cause sludge build up in the engine. It won't affect your car immediately but 80k down the line you'll have lots of gunk and crusties in your engine.
If you want flat out performance run the octane you can afford and adjust your timing up until it pings or you can feel that you're losing power and back off a degree or two. Just my opinion.