With the source of that comment found here:
I discovered it after reading this comment: How to make JavaScript run at normal speed in Chrome even when tab is not active? Playing an empty sound forces the browser to retain the performance. Has anyone encountered this? Would there be there a workaround for this suspension/slowing down? Would you call it a bug and should I file it as such? It would mean that we can't run background tasks, like for example checking periodically on a server using XHR calls and setInterval (I suspect to see the same behavior for setInterval, will write a test if time is with me). Couldn't find much on the internet on the subject. So it looks like Chrome suspends or at least slows down javascript execution in a tab that has no focus. It looks like the timeouts have been running a lot slower. Now if I run the test in Chrome and let it run in a background tab (so, switching to another tab and browse on there), returning to the test and inspecting the results (if the test finished) they are dramatically changed. Now I noticed that (as expected) setTimeout is not very accurate but for most appliances not dramatically inaccurate.
I was testing the accuracy of setTimeout using this test.