Web performance testing with the Grafana k6 browser and Grafana Faro involves using both lab data and field data to get a comprehensive view of an application's performance. Lab data, collected in controlled environments, is useful for early detection and resolution of performance issues, while field data, gathered from real user interactions, reflects actual user experiences under varying conditions. By integrating these two types of data, organizations can better understand and improve their web applications. Grafana Faro, a Web SDK, helps collect field data, including performance metrics and errors, offering insights into real-world user experiences. The combination of Grafana k6 browser and Grafana Faro enhances visibility into web performance, enabling proactive monitoring and more reliable applications. This approach highlights the importance of continuous testing, where feedback from field data informs and refines lab testing, ultimately leading to more robust and user-friendly web applications.