It all depends on your compression ratio. How many cc's in the combustion chamber. Octane is only a measure of the fuel's ability to resist detonation. Excessive heat and/or pressure causes detonation.
I would try the next octane higher first, if you're times improve, try the next higher, so on and so forth.
It's possible that a colder plug, by itself, would help you with the low octane. Finding the right combination is the goal, right plug, right compression, right fuel, right jetting, right timing.
"Tuning is tough" (Al Nunley)