Hi. (see edit)
Only suggestion then, is experiment with settings.
Not everything, but it should not take more than 20 minutes to up your fps by a couple.
1 - Turning off distant lands will allways improve fps arround Erothin, Dark Forrest etc. But remember to turn on when you leave these places or it spoils the whole look of Nehrim.
2 - Turn off shadows and turn down visibility settings by about 50%, test too see how much fps increases. If it increases enough for you, start increasing or turning back on what you miss most. Increased my fps by appx 10-13 in Erothin doing this. But everyones system is different. My way of thinking is to get a decent match of graphics and fluid play.
EDIT::
Another suggestion. Have you tried using OSR (Oblivion stutter removal).
I have just had a huge drop in performance on my pc (all my fault), have changed to win7 32 bit (having problems with mkv media files on 64bit) and it hits performance. Also now have some high textured mods in game. Bottle necked my pc .
So I decided to put on OSR, have turned multi-threading on in Nehrim setup , enabled it in the OSR ini.
Have set OSR to min fps 15 and max fps 40.
Only tested for a little while, but it is the first time I have ever crossed the bridge into Erothin without my fps dropping into single figures.