Kurt Shintaku's Blog - INFO: Extending Surface Pro (or Pro 2) battery life by adjusting the Power Plan “Maximum Processor State”
This has been floating around the Internet for years so it’s nothing new but for anyone that puts a premium on battery life on their Surface Pro (original or Pro 2) like I do (I specifically need to extend the battery because 90% of what I do with it is take handwritten notes using the stylus & OneNote) then this might interest you.
Adjusting Max Processor State in Windows 8
In order to extend the battery life a bit, all you have to do is change the the maximum processing power percentage assigned to the Power Options profile on your device from 100% to 80%. This provides a noticeable difference in battery life – some have reported up to 1-2 hours, & for most purposes like inking in OneNote or browsing, you’ll probably won’t see any change in performance.
To accomplish this:
Makes sense and it's easy enough to tweak too. Going to have to give this a try on my Pro...