Well remember Skyrim auto detects and does it pretty well, I've been getting a solid 60 fps and one day it just decided to lag every-time I fast travel to a city or a small village. And i end most of the stuff on my pc and only leave the essentials that barely uses disk or memory space . And it will most certainly not be the amount of saves, keep in mind I have one single save and if it auto-saves I just delete it and keep one. Games are developed that you should save quite a lot so that's not the prob as well :(