Yeah ... I can run Discord, Zoom, Meet - anything really, and my system doesn't have any performance problems. I open up Teams and usage jumps to 100% (MBP 13" i7 2016)
Still a bit confusing trying to find things but to be fair I have the same issue with most of these platforms.
I think this area will see an increasing amount of innovation and it's anybody's guess as to who will come out on top in the end.
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.