How Does Real User Monitoring Work? - New Relic Documentation
Real user monitoring (RUM) leverages the agents to dynamically inject JavaScript into pages as they are built. The injected JavaScript collects timing information in the browser that contains details to identify the specific app and the web transaction processed on the backend, as well as how time was spent in the app for each request. When a page completes loading in an end user’s browser, RUM sends the information back to New Relic asynchronously, so it doesn’t affect page load time. RUM uses the IP address to resolve the geographic location of each request.