Internet Explorer 9 (IE9) is the most power-efficient browser on the planet, Microsoft claims.
IE9, which launched on 14 March beat rivals from Apple, Google, Mozilla and Opera when Microsoft ran the five biggest browsers through six power consumption scenarios, the company said.
In a lengthy blog post thick with graphs, a trio of Microsoft managers laid out the results of those tests, which showed that on a Windows 7 laptop with a 56 Watt/hour battery, IE9 could be used for three hours and 45 minutes before exhausting the power supply. (The "56 Watt/hour" designation means that the battery can provide 56 Watts of power for one hour before it's drained.)
The closest competitor was Mozilla's Firefox 4, which came in at 3 hours and 35 minutes, just 10 minutes shy of IE9.
Other browsers, however, fared poorly in comparison.
Chrome 10, for example, lasted two hours and 56 minutes; Apple's Safari 5 two hours and 55 minutes; and Opera Software's Opera 11 two hours and 43 minutes, or 62 minutes less than IE9.
Not surprisingly, Microsoft stressed the importance of browser battery consumption.
"As computing becomes more mobile, and as the HTML5-based web becomes pervasive, it's important that browsers make power consumption a focus," said the Microsoft managers. "We hope and encourage the industry and other browser vendors to follow us on the path to a more power-efficient web."
Microsoft cited the browser's overall speed - "The quicker a browser can perform an action the less power the browser will consume," the managers said - and its hardware acceleration as reasons for IE9's win.
The company also criticised rivals, Google and Opera in particular, for their browsers' heftier appetites, noting that Chrome regularly pushed the notebook's CPU's and GPU's (graphics processor unit) power consumption, and that Opera doesn't hew to a Windows 7's default, causing that browser to devour about 5% more power than other browsers when it's idle.
Opera defended its browser's performance, and noted that the tests weren't conducted by a disinterested party.
"According to our engineers, they have obviously optimized for a battery scenario," said Opera spokesman Thomas Ford in an email reply to questions. "We have already reduced power consumption in Opera, and the fruits of that labor should be seen soon."
For its part, Chrome also said it had power consumption in its sights.
In an answering blog published Tuesday, software engineer Kenneth Russell said that Google had already instituted changes in the "dev" build of Chrome 11, and would roll them into the beta and stable channels soon.
Mozilla was simply pleased with the results. "We are happy to see that for the most common types of Web browsing today, we score very well indeed," said Mike Beltzner, director of Firefox, in an emailed statement.