Thank you for your reports. We released client and service updates this week, that address many MacOS-specific performance issues. We are also aware of recent performance issues with Microsoft Teams meetings, especially on laptops and when using external monitors.
The team is working to resolve these issues. In the meantime, please find troubleshooting information here: https://docs.microsoft.com/microsoftteams/troubleshoot/known-issues/teams-slow-video-meetings-laptops-4k.
We are happy to share that Electron 10 is rolling out to the public ring now, so you should notice improvements. We expect overall performance of Teams to improve even further with upcoming fixes around the calling and meeting features We will share another update as soon as we are able to.