Well every time I use a mod that adds any type of Custom content into the game, be it weapons or armor it freezes and stutters and is painfully slow to be around. I don't know if this problem is common I've looked around and haven't found much helpful. It only does it when I'm in the game space of the custom content. Any words of wisdom?

I've just discovered that it's to do with my Video options having the exterior and interior shadows on full, but my P.C can handle it easily and has done so before on my last umpteenth accounts. For some reason it's now decided it's too much when it never experienced these problems before. Is there anything i can do ?

Well you haven't given us your load order or hardware specs, could you get that info?

I've discovered it to be ENB series mod for Oblivion.