I think there's two reasons memory usage is lower. First, WebView2 is essentially just another tab in an already running browser process. If they're not pinning

I think there's two reasons memory usage is lower. First, WebView2 is essentially just another tab in an already running browser process. If they're not pinning to a specific version of WebView2, they're reusing the host machine's copy of Edge, which I believe is always running now, so startup latency is reduced. I think their numbers don't include the memory usage of this "always on" instance, and only count the Teams-specific memory usage. Second, Microsoft has done a lot of under-the-hood work to reduce memory usage of Edge on Windows that hasn't made it upstream into Chromium, so I suspect that gives them an additional decrease in memory usage simply by switching from Chromium to Edge-Chromium.