Anyone having battery-power issues?

I upgraded to 8 a few days ago (doing a clean install by usb after downloading Windows through the Upgrade Assistant) and everything about Windows 8 itself is great! Except that my battery-duration is really suffering. Before (and by before I mean, that same day, but using windows 7) I used to have like 6 hours of battery duration, sometimes topping at 8 hours with the energy saving plan. Now I'm lucky if I have 3 hours using using the energy saving plan. What I find the weirdest is that switching between energy plans doesn't gives me any gain.

Anyone noticed something like this on its laptop?