Skype is an Electron app currently. If you think current Skype is the better performer imagine the old Skype that was truly native.
Maybe I'm too old fashioned, I don't know. What I know is that creating multiplatform native application is really hell (I did that), and Javascript is much cheaper, that's why everyone is doing electron, which literally launches up another separate google chrome in your memory... Yes, it's cheaper, but memory is much more expensive nowadays, than it used to be when I started programming...
That's usually done by the browser when using WebRTC (except for postprocessing, e.g. background blur), not the application (using WASM or JavaScript).
Some browsers do this in hardware, others don't – just like some native videoconferencing applications are horrible CPU hogs, and others are quite efficient.