[admax88q]

That's also what Microsoft did.

It's quite possible that both results are valid. It sounds like there's big difference in the sites that Microsoft visited compared to Opera.

It seems an even better methodology would be to record actual user browsing sessions, and then replay them through different browsers and measure power consumption.

Opera's simulated browsing session does not sound particularly sophisticated IMO.

[Aelinsaar]

Couldn't you just make a giant virtual "browsing session" with hundreds of thousands of different sites , and crunch the numbers to minimize the background noise? MS has the computing power, that's for sure.