can 1 octane make this much difference?

Here in Australia we have 3 grades
I run 98 octane (10.5 360) as the normal fuel but we have 95 and 91 as alternatives.
87 octane what could run on that .
I have come down to the 95 octane at times depending what town I am in and it certainly affected the engine big time.

cheers

Benton