from the reining-in-rogue-tabs dept.
Google Chrome 57 restricts out-of-focus background tabs to 1% of a single core's CPU load, with exceptions for tabs that are playing music or maintaining a real-time connection to a server using WebRTC or WebSockets:
In September last year, the Chromium team said changes were coming to Chrome's handling of background tabs, but the changes have landed in the stable branch of Chrome a little sooner than expected. Basically, from now on, background tabs will be limited to an average CPU load of just 1 percent on a single core.
Chrome 57's actual mechanism for background tab throttling is a little more complex. After 10 seconds of being in the background (i.e. not in focus), each tab has a budget (in seconds) for how much CPU wall time it can use. (Wall time is the actual real-world time it takes for a process to start and complete.) The background tab is only allowed to use the CPU if it hasn't consumed its entire budget. Here's the kicker: the budget constantly regenerates, but only at a rate of 0.01 seconds per second.