I have Morrowind cities un-mod, are there any other mods which improve performance? I am using FPS optimiser.

So you've got scifiguy52's "Morrowind Un-Mod" and "Balmora Un-Mod" by Mouse? Between those two that's all the cities on Vvardenfell with decorative statics and so on removed. What else were you looking for? Something removing trees and rocks from the wilderness?

I don't know of any other mods similar to those two, there's FPS Optimiser's "Hide objects smaller than " slider, which I guess you're already using.