Large modern web applications, developed in smaller autonomous pieces by different teams, can enhance scalability and autonomy, but monitoring the performance of individual components and the overall application is challenging due to numerous external factors. The browser performance API offers a native solution for measuring performance-critical tasks locally, while New Relic has introduced a new data collection integration, BrowserPerformance events, to automatically capture native performance marks and measures across applications. This tool aggregates these metrics into a comprehensive dataset, allowing teams to pinpoint exact timings and evaluate performance across various components and pages, ultimately facilitating optimization and performance analysis. By using the New Relic browser agent, teams can gain insights into how components perform in real-world scenarios, set alerts, monitor dashboards, and make data-driven decisions to enhance their code. This approach, along with the use of standardized marks and measures, offers a holistic view of web performance, enabling effective identification and resolution of performance bottlenecks.