Lazy-loading is used by Sentry to improve the efficiency of its User Interface by reducing the time it takes for data to load. Instead of fetching all data at once, Sentry splits the request into two parallel requests, showing the results immediately after the first request finishes. This approach allows users to see some data almost instantly while waiting for other data to render. By using this technique, Sentry was able to achieve a 22% faster UI and save half a second in load time. The goal is not only to provide error monitoring but also to ensure that customers can see the data they need in a timely manner.