This past week, Microsoft released a new report showing how its Edge web browser delivers superior battery life. Now, the software giant has explained how it delivered these improvements as part of the Windows 10 Creators Update.

As it turns out, the report leaked online a bit early, and Microsoft had intended to discuss the results in a blog post that accompanied it. That blog post is now available.

“Windows users spend more than half their time on the web, so improvements here have a significant effect on your device’s battery life,” Microsoft’s Brandon Heenan writes, explaining both the focus and the coming release of Windows 10 Cloud. “We’re committed to giving you the best, fastest, and most efficient browser possible.”

Despite vague promises to change this, Microsoft still updates Edge with major Windows 10 releases only—or what Microsoft calls feature updates—so Edge isn’t updated as much as its competitors. Because of this, and because of its newness, Edge still lags behind major browsers like Chrome and Firefox from a functional perspective. But the one area in which it continues to dominate, and I think we can actually credit its OS ties-ins for this, is battery life.

“Comparing the latest versions of major browsers on Windows, the trends are similar to what we’ve seen with previous releases,” Heenan explains. “According to our tests on the Windows 10 Creators Update—based on an open-source test which simulates typical browsing activities across multiple tabs—Microsoft Edge uses up to 31% less power than Google Chrome, and up to 44% less than Mozilla Firefox.”

But the most interesting part of this discussion, I think, is the how. That is, how does Edge deliver such impressive results compared to its more battle-tested competition?

According to Heenan, it goes like this.

More efficient iframes. “Today, lots of web content is delivered using iframes, which allow web authors to embed documents within their own webpages,” Heenan explains. So Microsoft made Edge’s handling of iframes more intelligent by throttling non-visible iframes on web pages. “Users won’t notice any difference: the iframes still load and behave normally when you can see them,” he explains. “We’re simply reducing the resources they consume when they’re not visible.”

More efficient hit testing. Many websites are overloaded with advertising and other elements that constantly perform computationally expensive “hit tests” to determine if they’re visible. Edge now performs these tests more efficiently, and neither web developers nor users will notice any difference, “other than a faster experience and more battery life.” Microsoft has also created a standards-based framework for web pages to accomplish the same thing without needing to constantly check for visibility themselves.

Treat Flash like the second-class citizen it is. In the Creators Update, Edge now blocks much Flash content by default, and it gives users more control over which Flash content they see. “Not only is this good for battery life, but it will help improve security, speed, and stability,” Heenan says.

Telemetry-based improvements. Edge incorporates “countless” efficiency improvements based on telemetry in the Creators Update. (Which is unlikely, but let’s move on.) “As with any release, we’re tweaking and improving what’s happening under the hood in Microsoft Edge,” Heenan writes. “Recently, we’ve been using telemetry from real devices to measure how much time we’re spending responding to different APIs in JavaScript. This view tells us which functions we spend the most total time responding to across all devices, so we can improve those first and get the most bang for our buck.”

Heenan promises further battery life improvements in the future. Hopefully, we won’t need to wait for Redstone 3.

Tagged with Chrome, Firefox, Microsoft Edge