Chrome starts throttling background tabs to prolong battery life

Google says background tabs are responsible for a third of Chrome's battery usage.

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Credit: Google

Google is bumping up Chrome’s battery-saving chops once again with Chrome 57, which started rolling out to users last Thursday. Beginning with Chrome 57, the browser will limit how often a website’s JavaScript functions can run when its tab is not in focus for the user.

In other words, the activity of background tabs is going to be throttled. The only exception to the new policy will be sites playing audio or anything that requires real-time interactivity via WebRTC and WebSockets. These special cases will continue to operate as normal so that the user experience is not compromised.

Google says that background tabs can consume up to a third of the browser’s power usage on desktop PCs—though laptops would clearly receive the most benefit from this tweak. Reducing the amount of power these tabs use is clearly a good idea, but without testing its hard to say whether this policy will result in noticeable power savings for users. As we’ve noted before, however, testing browser battery life is not a simple task.

The new throttling policy should mean the average user will end up with about “25 percent fewer busy background tabs,” according to Google. That not only means better battery life, but an easier load on the processor, which could mean a more responsive experience on devices with slower processors.

The story behind the story: Browser makers are always working to create software that consumes less power. Over the past nine months or so Microsoft and Google have been engaged in a showdown over battery usage. It started last June when Microsoft showed Edge running 70 percent longer than Chrome on Windows 10. A few months later, Chrome was touting the efficiency of Chrome 53, which lasted longer than Edge originally did in Microsoft’s tests.

For those who don’t care about battery usage and just want Chrome to use all the power it needs there appears to be a flag for that. Type chrome://flags/#expensive-background-timer-throttling into the address bar, hit Enter, and set that flag to Disabled. Be warned, however, that Google created this flag in late 2015 as a way for developers to test JavaScript, not as a tool for everyday users.

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