React is fast, thanks to the VirtualDOM. Using a diffing algorithm, the browser DOM nodes are manipulated only when there is a state change. This algorithm is computationally expensive. Using webworkers to perform the calculations can make React even faster.
Debuted in a session at ReactConf 2015 and has been used to benchmark many javascript frameworks. It shows an application simulating DB queries.
To see frame rates, open Chrome dev tools, enable Show fps meter in Console > Rendering
The canonical app that every frontend framework uses as a demo. Shows how events are passed from the UI thread to the worker, and how DOM manipulations as sent back to the UI thread from the worker thread.