Profiling React applications for Performance was introduced in React 16.5 using a React Profiler DevToolsplugin, this works but not straightforward. To get this working we need to open the developer tools, record the performance metrics and later analyze the results. Also it records the performance of all running React Apps.

React 16.9 introduces the new React.Profiler component which avoids the drawbacks of the earlier DevTools based Profiler. The Profiler API is programmable and we can configure it only for specific applications. Also the Profiler API does not need DevTools support it can capture and write performance logs to the console directly.