I'm not particularly familiar with Electron and WebView2, but even the Electron blog suggest that WebView2 uses some different IPC formats that can be faster[1]. Considering a big selling point of Teams is as a hub for other Microsoft products, and other plugins, it doesn't seem unreasonable that improvements to the IPC would translate to better performance for Teams, in at least many of the expected usecases.

[1]: https://www.electronjs.org/blog/webview2/#performance-discus...