So, after a week of testing, here are the results. And you won't be surprised to learn that Opera's claims appear to be advertising puffery.

I modified my testing to run each of the three browsers, Opera, Chrome, and Firefox, with a full battery to 50% rather than to 0%. I quickly realized that trying to drain the battery to zero would extend my testing to two weeks (or more given that I have a busy schedule this coming week) while hitting 50% with all three browsers seemed a realistic compromise that would avoid the pitfalls of a shorter test duration. Each test was done in three segments: 45 minutes, 45 minutes, and 2 hours 15 minutes. Why? That's just the way my testing with Opera was structured given my schedule and I adopted it for the other two browsers. In addition, I did mostly light browsing with little video other than that embedded in sites like Facebook, the Washington Post, and the New York Times--no Netflix, no YouTube marathons. Three or four tabs open at most at any one time. All three browsers had ad block software running.

And there was absolutely no detectable difference in power usage amongst the three browsers. Each ran the battery down to 50% after 3 hours 45 minutes of usage, which was consistent with my previous experience regarding the power usage of my computer. In addition, Opera's "power saving mode" doesn't remain on when you close the program, and you must remember to reset it each time you start the browser. I also noticed that it appeared inconsistent as to whether it worked when a new tab was opened--sometimes it remained turned on and sometimes it didn't. Of course, given the results, inconsequential but irritating nonetheless that I had to monitor something that should have been made permanent in the settings. You might also note that in comparison with my early results with Opera, my savings diminished over time.

Given no discernible power savings advantage and the clunky interface to activate the power saving mode, there's nothing about this new "feature" that should make you want to use Opera. Power savings are probably solely related to the use of ad block software. There may be other reasons to use Opera, but not this one.