I don't think it's safe to generalize "x is slow and electron, y is fast and native" to mean "native is fast". Electron lowering barrier to entry also means it's used by projects who aren't going to carefully profile their app no matter what, so the same app written as a native app would also be garbage. At least some of it is "correlation not causation"

And for your chat example, when I was at IBM the Sametime chat native app couldn't even accept single line incoming text without grinding a several thousand dollar machine to a halt. Bad software is going to be bad no matter what language it's written in.