Larian Studios Forums Baldur's Gate III Baldur's Gate III - Technical & Gameplay Problems Slowness on MacOS since October 1 update

Indeed. This is a regression. I think something similar had happened with Patch #21, which had again broken Mac performance.
My two cents: the performance drop with Patch 7 vs. 6 is so noticeable (not just the frame rate loss, it also stutters) that I will wait even if I was in the middle of a play through (any play through).