[somewheres]

Gee, maybe it's because you have a million tabs open, and all of them are websites with shitty, wasteful javascript begging the CPU for useless operations to update every single tracking pixel and cookie, with up-to-the-minute anaylitics, attached to sessions that are years old, on how your eyes move over their ad banners, so that a genetic machine learning algorithm can determine which ads are most likely to convert to clicks and then sales.

Hint: It's the ad for the top 7 ways you didn't know you could get bunions, and there's a 50% chance it will convince you to buy new shoes.

[PhantomGremlin]

You are being downvoted, I assume for your "over the top" tone, but your overall message is very good. User behavior is the largest determinant of battery life.

I run Firefox with NoScript, and my battery usage is always very very good. An additional benefit is that I see few ads, since they invariably rely on third-party javascript.