I'm using Linux and Windows on an AMD Threadripper 1950x (16 cores/32 threads) and PI does a good job of keeping all the threads busy when processing large numbers of subs.
You might be able to get a better feel for general performance on Mac by looking at benchmark results:
http://pixinsight.com/benchmark/ Most of the results are for Windows and Linux but if you look hard there are some Max OSX results too.
Cheers,
Rick.