The overall results are, of course, subjective beyond the device and battery size in question too. For tests with YouTube running in the foreground and 36 background tabs, the company notes 13-percent in savings. Or around 36-minutes. So there may also be some direct correlation to the number of tabs open too.
There's certainly dependence on what, exactly, users are running in the foreground, though. With a blank foreground tab, the improvement is closer to two hours.
Chrome is looking to compete where it matters with battery and memory savings in under a month's time
Now, Google obviously has its work cut out with this feature. It's going to need to weigh the cost-benefit of gaining new users or retaining those with cutting away at how much activity background tabs can engage in. And it may take some time for the company to optimize the changes so that they're ready for the Stable Channel. It will almost undoubtedly become even more efficient moving in the interim.
At the very least, this won't arrive until Chrome 86 does. That's currently slated for the first week of October — or the second week for Chrome OS.
In the meantime, Google has also been working on memory-saving features with Microsoft. So this appears to be part of a broader test to instantiate improvements that will make the software more competitive. As that other test stands, at last reporting, it was saving as much as 200MB of memory at a rate of around 27-percent.
With both memory and battery savings in place, it should be fairly easy for the world's most popular browser to maintain that position.