I read somewhere that Porsche estimated that turning off PSM might gain a few seconds on the Nurburgring in the hands of a very experienced driver.
I doubt there is much if any gain for most of us racing driver wannabees in DE (and even if there is so what?). I sure wouldn’t turn it off in my car. I only have ever had it engage once on track – during IDS on the development track but the doesn’t mean it won’t save my car or life sometime in the future