In the 118,000 miles I have collectively put on my 2013 & 2015 F6B's I have saved $1242 by using 87 octane.
I did quite a bit of dyno testing years ago and learned my lesson then. If your engine doesn't have enough compression and/or ignition advance to burn higher octane it will actually detract from the performance. Higher octane fuels are made to control detonation and will burn slower.