Shadow detail seems to be the setting that is the most demanding.

[Beriallord]

I got an I5 2500k with a Radeon 6950, on full ultra everything, including shadow detail I get FPS sometimes in the teens in town, basically unplayable. But if I take Shadow detail from Ultra down to High, I get 50-60 FPS with no stuttering. I hope this helps anyone else having performance issues with a similar system to mine. The shadows are done really crappy in this game anyway, you could even turn them on low if you wanted, and leave everything else on High/Ultra, even FXAA and reflections enabled.

[ogridum]

Ive been testing over and over with different skyrim.ini and skyrimpref.ini configs.

 

I would say that ugridstoload, shadow configs from skyrimpref/launcher, fxaa, anisotropic filtering, antialising and multisampling and fxaa are the things that bog down the system the most.

 

Things like adding shadows to trees and rocks dont matter much, because what matters is the distance the shadows will be rendered, but even more important than the lod is the size of the texture used.

 

Ugridstoload from 7 to 9 to 11, have the biggest effects on FPS. Just changing one to another and being in Whiterun plains on top of a tower (best place to test so far) means 20 fps difference per setting.

 

Increasing the fade distance, lod and quantity of rendered textures for grass/trees in skyrimpref.ini affect the FPS very slightly.

Adding all reflections on water and being in Ivarsteed falls, for example, doesnt affect the FPS much, but adding multisampling to water, means a huge FPS drop.

 

 

Took me 6 hours yesterday just going back and forth between dozens of suggested configs in atleast 6 major forums threads about skyrim, individually researching each parameter, changing values, comparing screenshots and benchmarking 60 seconds with fraps.

 

To me the best tradeoff is sacrificing shadows quality for a higher ugridstoload.

The problem with shadows, is that even if you have 4 times the original texture quality for shadows and increase the exterior distance, it will still make shadows "twitch/flick", due to how the high distance force the shadows to update more often. That sucks. It would be awesome to have long view distance with everything having shadows without flickering effect.