Indoor Fog/Particle effect and being around lots of fire seems to hit me on my setup. Anyone have any experience with halfing the particles loaded or any other .ini changes to help fix this? Small stutter sometimes indoors and I know its due to these fog/flame effects. Sigh AMD drivers :/
Any negative impact to halfing the particles from my 700 to 350?
Here's a few mods you can try, I have not tried them myself but they were recommended for better visuals/performance by another user on 3D Vision forums:
Exterior Fog
http://skyrim.nexusmods.com/downloads/file.php?id=9930
Interior Fog
http://skyrim.nexusmods.com/downloads/file.php?id=9571
If that setting that halves particles actually does anything, it should help improve performance. There's also settings for each fog/particle effect system in the Creation Kit that I saw, but changing or removing all of those will take some time.