Hello! It's my first post on these forums.

I've been having some problems with Skyrim, back in March I purchased and played it for many hours without any problems but minor glitches like NPCs randomly following me and such. Only now I got enough time to play the game for real, I did a clean install through Steam and purchased Dawnguard and Hearthfire. Through the first quests escaping from the execution in Helgen I noticed major slow downs after some time especially while "Autosaving" (But not necessarily, happens when entering or leaving a room or just randomly) the FPS drops to below 10~5, when I ALT+TAB out and back to the game it gets back to normal but it's really annoying. Here are my system specs:

Windows 7 64 Professional
Core i5 750 @ 3.6Ghz
Asus P7P55D Deluxe
8GB Ram DDR3-1600 (cl8)
eVGA GTX 460 1GB FTW (306.97 drivers)
27' 1080P Monitor
128GB SSD Crucial M4
2TB(1+1) WD Black RAID0 (Skyrim is installed on this drive with Steam)

Temperatures are OK, GPU wont get over 62oc, CPU stays around 40-50oc, HDDs are also perfectly healthy.

No software running in background but Steam and my anti-virus, I have Avira Premium but I've tried disabling and didn't seem to affect the performance at all.

I've also tried turning the settings down and didn't help. Game used to run very smoothly back when I first tried it on the same computer.

Any clues? Thanks!