Why do you care? Serious question.

Have you ever compared the system resource demands of emacs and vim or neovim when you add enough plugins or extensions to reach feature parity with VS Code? They get to be just about as demanding on your disk space, ram and idle cpu.

It may be an Electron app, but a lot of custom engineering has gone into the core text editing stuff - https://code.visualstudio.com/blogs/2018/03/23/text-buffer-r...