Krauter, as far as my mods are concerned, you should definitely upgrade from V1.1 and patch V1.1.1 of my interior mod to just V1.2. That will clear up some mod soup issues. And, you could switch to the LR version of my shadow improvement mod. LR stands for Low Resource(system resources)
And, you can always use the D3D9 fix, it does wonders for FPS. Here, I have packaged it into a JSGME compatible mod:
http://www.mediafire.com/?3spsbtjka3j22v2
Also, Icebergs v1.3 - Vikingers Lite Campaign Compatible, does cause some rather strange issues. You might try running the game without it, although it would require starting a new campaign.
Hope this helps.