Sure, and I'm not trying to defend the performance of Firefox on MacOS (I wouldn't know). But it's easy to see why it's not necessarily Mozilla's highest priori

Sure, and I'm not trying to defend the performance of Firefox on MacOS (I wouldn't know). But it's easy to see why it's not necessarily Mozilla's highest priority. Hell, there are probably more Firefox users on Windows XP than Firefox users on Linux (this may sound like hyperbole, but I know for a fact it was true as of no less than five years ago).