PerformanceContainerTiming: paintTime property
Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.
The paintTime read-only property of the PerformanceContainerTiming interface returns a timestamp that represents when the rendering phase ended and the paint phase started.
This property is a broadly interoperable metric for indicating the time to paint, and can therefore be used when comparing behavior across browsers.
For single-browser testing you can presentationTime instead.