Chrome has always, to an extent, throttled tab performance when said tab is in the background. This activity has been more aggressive on mobile devices, but with Chrome 57, the desktop will see more proactive throttling.
What That Means
In general, throttling is the process by which software purposefully limits the amount of processor drain from any given application or service.
As I said above, Chrome has been doing this for a few years, but up until now it has been more aggressive on mobile and left the desktop to be a bit more free to keep processes running in the background.
With Chrome 57, this process will get a much-needed change that will throttle background tabs much more aggressively. According to Google’s Developer Blog:
Work in the background should be kept to a minimum unless it’s absolutely necessary to provide a particular user experience.
There’s some really technical stuff that goes into all this, but in laymen’s terms, this new setup will allow Chrome to limit background activity to 25% fewer busy background tabs. Unless you are a developer, that’s all you really need to know.
What Is Gained
The biggest gain from this change is battery life. Eventually, Google wants to limit all background tabs activity and instead rely on new APIs for service workers to do all the background work. For now, however, this gets all open tabs to a very minimal activity level, and that means some decent battery gains.
For devices with less RAM, this can only boost performance in general. With tons of tabs open, it stands to reason that if those tabs get performance throttled, more system resources can be given to the task at hand.
Battery gains and performance boosts? That’s a win all around.
Additionally, Google says that tabs with things like music or video won’t be susceptible to this throttling for obvious reasons. Hopefully Chrome will keep all this straight and we won’t see skipping or stopping playback when we switch focus to another task for a period of time.
For a time there were some who thought Chrome was going the way of IE, getting more and more bogged down with battery and performance-killing processes. It is great to see Google continue working to enhance Chrome’s ability while remembering that speed and battery are of utmost importance.
SOURCE: Chromium Blog