What performance metrics did you monitor? Did you have to debug any metric?

In working with the frontend, I usually monitor performance metrics such as First Contentful Paint, Time to Interactive, and user interaction delay indicators like First Input Delay. For debugging metrics, I often use browser tools such as Chrome DevTools Performance and Lighthouse.

For example, I once noticed that the page load time significantly increased after adding a new component. Using a profiler, I identified that a heavy operation in the component was blocking the main thread, and I optimized it by breaking it into asynchronous parts, which improved the Time to Interactive metric.