It’s been really solid for me since that major overhaul they did a couple of years back.
Not sure what issues you have, but I wonder if perhaps that us NOT running 3rd party security products is a factor (we only run Windows Defender).
If you want to paraphrase my reply it would be more like:
“It works for some people, it doesn’t work for some people, what might be different between those groups of people?”
Let me say this again, Teams works perfectly on my machine, it's largely indistinguishable performance wise compared to Slack on the same machine, if anything it runs a bit better.
I'm not going to try claim Teams isn't in fact terrible for other people, my point was that as I suffer no problems with it, it makes me wonder what's different on my machine compared to these other people's, and as I don't have any security software except Windows Defender, I speculate it's maybe their corporate managed security software is a factor.