Performance testing and debugging are crucial yet often overlooked aspects of application development, particularly for React-based applications dealing with complex data flows. Effective performance profiling tools include the Chrome Performance tab, the Profiler from the React Chrome plugin DevTools, and React's official Profiler API, each offering unique features to identify and address performance issues. The Chrome Performance tab is framework-agnostic, making it useful across various projects, while React DevTools provides insights into component performance with a flame graph and commit analysis. The React Profiler API allows for customized metric tracking directly in the source code, enabling developers to measure rendering costs and improve performance through targeted interventions. A mixed approach using these tools allows developers to adapt their processes for continuous integration and efficient feedback on new code implementations, thereby enhancing application reliability and efficiency.