There are some great improvements in 3.5.2 (including CPU cycles being released a LOT sooner when switching between patches/different plugins) BUT I had a full machine lockup caused by MainStage in my first gig using 3.5.2. I’d spent about a week testing it upon release and felt comfortable using it at a gig; in the third song, my machine completely locked up and the screen started displaying really weird artifacts and eventually went completely bright red. I had to reboot and then used 3.4.4 for the rest of the gig.
I submitted a bug report and the Apple engineer replied to ask for more system diagnostic data. The lockup was apparently caused by something related to Metal but whether it was MS itself or a plugin is unknown. Regardless, I won’t be using 3.5.2 again.
2020 MacBook Pro 16", 2.4 GHz 8-Core Intel Core i9, 64GB RAM, 2TB SSD, OSX 11.2.3 RME Fireface UFX+
MainStage v3.4.4 / v3.5.3