I don't think the higher octane fuel burns at a slower rate. I'd say it's a more stable controlled burn from the point of ignition across the combustion chamber. The higher octane makes it more difficult for "hot spots" in the combustion chamber to pre-maturely ignite the fuel. I doubt you could in any real world testing accurately measure any power loss from low octane to high octane. Assuming of course neither one was pre-igniting.
Yeah, using 110 octane when 91 octane will do the job is wasting money. The term "Valve Rattle" as it relates to pre-ignition has been around a long time, like myself and Ron, it's "old school". Still a useful saying to convey the basic message.
