WPT details: This intervention doesn't require changes to the spec. Timers are already covered by Web Platform Tests.
Enter Intensive Wake Up Throttling after 10 seconds if the page is fully loaded when it becomes hidden. Currently, wake ups from JS timers with a nesting level >= 5 are throttled to 1 per minute after the page has spent 5 minutes in the background [1], which is very conservative and was chosen to allow a launch of Intensive Wake Up Throttling with minimal regression risk. We're now planning to reduce this timeout to 10 seconds if the page is fully loaded when hidden. [1] https://chromestatus.com/feature/4718288976216064
This is expected to extend battery life. An experiment on the Canary and Dev channels did not reveal any regression to our guiding metrics and there are significant improvement (~10%) to CPU time when all tabs are hidden and silent.
Docs: https://docs.google.com/document/d/1WFyfKUUxqM7uKxKOGhLiOjyY6T7QRduVcuHN0f6vJkk/edit