J-S-Q:
I was a Mac user for many years -still am, but just not for my studio computer. Purely anecdotally (from seeing stuff online and from talking to friends) it does appear that Cubase currently runs slightly better on Windows. Anyway, I’m not sure if there is much difference between Mac and PC with this particular issue and I think to some extent it is present in all DAW’s. It’s easy to test:
Take the plugin of your choice
Create an audio track with 8 instances of that plugin.
See how many times you can duplicate that track before the audio starts breaking up/crackling
Now repeat the process but instead of duplicating the track, route it to a group track with 8 instances of your chosen plugin. Then route it to another group track with 8 instances etc. You will find that the number of plugins you are able to run is vastly reduced if they are chained through multiple groups compared to if they are all on separate audio tracks.
Yes, I did this exact type of test a couple years ago when I first switched to Cubase and noticed that it hit the redline far sooner than both Pro Tools and Reaper (Reaper using the same VSTs/plugins as Cubase) did. Again, that was just my specific experience when doing this kind of testing.