My Linux and MacOS machines behave exactly as the parent suggests, it completely melts my laptops (and my laptops are not slouchy, i7-2020 MBP and a Precision 5520 with a Xeon E3-1505m).
In fact, it's often the case that after a meeting teams will continue using 100% of a CPU core until it's restarted.
Perhaps it's better in Windows?
Due to this, and as the notification system is designed by a sadist, I switched to using it in a browser, which unfortunately means you can only see one person at a time on calls for some reason.
It is now not uncommon for me to join calls twice at once from browser/app each, and juggle audio/speaker/camera settings for a bit to do demo's, then killing the native app.
I can at least get native notifications & not convert my PC to a space heater this way, but it's still pure bullshit.
I had a brief hope when I found some reference to native notifications in a config file, but that was a dead end.