This is repeatedly recommended, but I think it's overlooking that not all manufacturer customization is entirely evil. You then to hunt down all the drivers for bits of the motherboard. Are you sure your power consumption settings are optimal after you've done this?
Windows has gotten pretty good at finding and installing drivers for you. I'm not sure about 8.1 (only used it briefly on a tablet that came with it installed) but with the 10 preview it has found and installed all the drivers I needed for the two Thinkpads I tried it on. It didn't download the Lenovo power management utility which is key to really squeezing the most out of it, but in my experience it isn't significantly better than Windows power management + keeping the screen brightness down (which is what the Lenovo utility does anyway).
