We instrumented our frontend test suite using Sentry's Performance Monitoring instrumentation, which is tree-like in structure with a transaction as the root node and spans as child nodes. We used Jest-circus to listen to events from Jest by defining a handleTestEvent method. The slowest tests were larger page views with many subcomponents, and we found that the beforeEach function was slowing down due to the store triggering change detection in components that should have been unmounted. We added a componentWillUnmount to the class component being tested and used Sentry's Performance Trends feature to confirm the performance impact of these changes. By making these changes, our test has its overall total time cut nearly in half, and we were able to identify the root cause of the slow test.