I want textures, models and resolution on highest possible. However my PC lags with it.

What are the best things to sacrifice -other than these - for better performance?

I dont really care about shadows but my friend says that shadows dont affect performance much?

Shadows actually has one of the biggest impact on performance.

Ok thanks, I'll put shadows on low then. Could you give me tips on what else I could take down abit? Is view distance a killer aswell?

One last bump.

Im considering lowering anti aliasing more but have it at only 2x atm and afraid the game will look crappy without it.

I found the shadow quality setting to have the greatest single impact on my game performance. I have a very, very modest system and this is what I have done: I have turned off AA, AF, and FXAA completely and turned shadows to low. This has enabled me to turn all the view distance sliders to max, enable all water reflections, and set textures to high. The game looks beautiful and runs very smoothly.

Thanks! : )

I run 2 older 8800 gt cards in SLI. Shadows, more than 4x AA, and FXAA drag my system down. I have actually found FXAA to look worse anyways so I wouldnt use it if it didn't. If you use ambient occlusion, use the performance setting or it will kill your frame-rate on a mid-range or older nvidia card. Shadows seem to be the biggest killer in this game- If I use med or lower shadows I can crank everything else up to high/ultra, as long as my AA is 4x or less, and ambient occlusion is set to performance. I turn off AF in skyrim options and force it (and ambient occlusion) through nvidias skyrim settings at x16. It looks much better and has a minimal performance hit. Here is a good tweak guide put out by nvidia that explains some of these settings and how they affected the performance of a 560ti:
http://www.geforce.com/Optimize/Guides/the-elder-scrolls-v-skyrim-tweak-guide?sf2686171=1

If you don't care about shadows and don't mind messing around with ini files, change these settings in SkyrimPrefs.ini:

iBlurDeferredShadowMask=0
fShadowDistance=0
iShadowMapResolution=1

This will effectively disable all shadows (both indoors and outdoors) without disabling their associated light sources. You should see a nice performance boost.

goats and babies.

Works for me every time.

Quoting for the lulz.

Lose the texture mods. Sorry, but you did ask.

The 3 most effective things:

Antialiasing - Have at 0 or 2x
Resolution - have it as low as possible but still nice looking for you.
Shadows - Have completely off if not too fussed.

If you really want high res textures, those 3 are your focus.

Lowering other things give slight performance boosts, the ones I listed are the major things.

My personal settings for nice looking but less performance-intensive shadows:

iBlurDeferredShadowMask=8
fInteriorShadowDistance=2000.0000
fShadowDistance=2750.0000 (you can use a smaller number for more fps, but shadows don't extend as much away from you)

iShadowMapResolution=2048 (use 1024 for more fps, but will lose quality)