Redmond took four Surface Books and streamed a high-definition video wirelessly on each device using Edge, Chrome, Opera, and Firefox. Average power consumption put Edge in the lead. Chrome, Opera (with battery-saver mode enabled), and Firefox came in second, third, and fourth, respectively.

“Microsoft Edge lasted three hours longer than Google Chrome—long enough to finish the final movie in your favorite trilogy, while the competition stalls out halfway through,” Microsoft said in a blog post.

In a separate post, Microsoft promised “dozens of improvements to power efficiency” in the upcoming Windows 10 Anniversary Update, including more efficient background tabs, Flash running in a separate process, as well as an optimized user interface and networking.

“When it comes to energy efficiency, we’re never really done, and you’ll continue to see this level of investment over the coming releases,” wrote Microsoft Edge program manager Brandon Heenan.

Windows Insider members can now preview the improvements, which are due for public release this summer.

Last year, Google promised “a ton of improvements to make your browsing use less memory and power” with Chrome 45. Chrome lets you “continue where you left off,” or return to the tab you were looking at when you last closed the browser. But that can be labor-intensive, so with Chrome 45, you’ll find tabs restored from most to least recently viewed, “so you get to see the most important tabs faster,” Google said.