As a website owner, I really hate that 'feature', it really screws up the exit rate in my site stats (I don't run ads on my sites.)
https://developers.google.com/chrome/whitepapers/pagevisibil...
This is only for prerendering. I think joshuahedlund is right about prefetching.
Chrome also does prerendering in some cases, which runs JS, fetches stylesheets, etc. The user may or may not ever see the result, of course.
As a website owner, I really hate that 'feature', it really screws up the exit rate in my site stats (I don't run ads on my sites.)