On Mac, after two hours of rehearsal with ~40 participants, the UI becomes unresponsive. A click may take 20s to execute. top shows a processor usage of 103%. (As compared to 35% one hour earlier, with the same number of participants.)
The Mac mouse cursor changes into the "spinning beachball of death", as it is commonly reffered to.

CPU usage shouldn’t grow over time.

I’m on macos 11.3.1 on a 2.9 GHz 6-Core Intel Core i9 MacBookPro (definitely not underpowered). I’m using a USB audio interface Focusrite Scarlett 4i4.

The behaviour was observed on Jamulus 3.7.0 (obtained as a .dmg from jamulus.io) AND on Jamulus 3.8.0beta1 (which I compiled myself).