VS Code doesn't provide direct DOM access to extensions authors, that's definitely a deciding factor. But a couple of years ago even simply writing inside Atom

VS Code doesn't provide direct DOM access to extensions authors, that's definitely a deciding factor. But a couple of years ago even simply writing inside Atom without using any extension felt sluggish to me. TypeScript gets downcompiled to JavaScript anyway, so I don't think that's directly a contributing factor, but maybe because of the type system they can spend less time debugging and more time optimizing.