The only part that's translated to native APIs is the rendering itself. Instead of rendering a WebView with an HTML <button />, it renders a UIButton from the native UIKit.

The app logic is still in Javascript, never compiled to another language.

IMHO this is perfectly fine. I have a fairly large app in react-native, and most users that have tried it are fine with its performance. Scrolling in lists and maps, being native components, is as snappy as in a real native app. I'm only having performance issues in page transitions, and I think I can fix that with a bit more work.