The download size of Bitwarden for Windows waws 694 kB. Less than one megabyte. It was allocated some 90MB of RAM when running. I don’t know how much it actually uses of that. But it is hard to see how that would be a resource hog in any sense. Again, the benefits of a native app are very minimal.
I think Electron has been a great success. It has allowed so many apps to get a standalone app with only quite little extra development effort. It helps to get consistent UI across web and the app. And as I said really minimizes development effort.
At least on new computers I have never felt that Electron apps are slow. Visual Studio Code is de facto web app editor because it works so well and because the development is so fast. It being electron has made it easy to offer the same editor on web pages too. In my opinion the slowness of Electron is a myth and at least greatly exaggerated. I never looked back after switching from Sublime Text to a Electron editor (VSC). And BW is way less sensitive to performance than VSC anyway.