Chrome DevTools Timeline panel provides an overview of all the activity in an application as it runs: fro example, processing DOM elements, rendering page layouts or painting elements to the screen. It can break this information down in three different ways: by events, Frames or Memory usage.
The Timeline won’t display any information by default, so to begin a recording session, you need to open your app and click on the grey circle at the bottom of the pane (or just use the Cmd/Ctrl + E shortcut). The record button will now turn red, and the Timeline will begin to capture information.
Complete a few actions inside your app and after a few seconds, click the button again to stop recording.