New metric : CPU abuse


As a consultant I see more and more sites released that freezes the old browsers like IE7, by abusing JavaScript. That’s generally because the developer does not really check old browsers and makes heavy use of DOM manipulation (without even noticing, thanks to jQuery and plugins).
From time to time, there is a also a badly coded Flash ad that freezes everything.
The WPT waterfall is about the network, the screenshots are about the rendering but there is currently nothing that can warn about CPU hogs.

I would like to be able to

  • detect sites that freeze the browser
  • monitor that, a bit like the speed index you created

I made some code and integrated it in my WPT private instance. It reads through the _progress.csv file that contains all CPU % and a timestamp and does some math :

  • count the number of time the CPU is 100% more that half a second
  • average and median load
  • CPU cost (the sum of all the percent)

Does it interest somebody ?
Do you think CPU hogs of half a second is representative on how the interface is fluid ?

If so, I will share the code at will