React Native provides a near-native experience while using a shared codebase for both iOS and Android. Unlike native development, which requires separate codebases and expertise for each platform, React Native allows for faster development and easier maintenance, reducing the overall development effort and cost.

Yes, existing native apps can be converted to React Native. React Native’s ability to integrate with existing codebases means that parts of a native app can be rewritten in React Native while still leveraging native components. This allows for gradual migration and the ability to take advantage of React Native's benefits over time.

React Native offers several advantages, including a unified codebase for both iOS and Android platforms, faster development and iteration cycles, and a large ecosystem of libraries and tools. It also supports hot-reloading, allowing developers to see changes in real-time without recompiling the entire app.

React Native handles performance through native components and optimizations like virtual DOM and efficient rendering. For user experience, it provides access to native APIs and modules, ensuring a responsive and smooth interface that closely mimics native app behavior. Performance can be further enhanced by optimizing code and leveraging native modules when needed.