Making larger settlements look like small ones

Hello. I'm guessing this fits better in the mod chat than the modding questions section as there's going to be several files that will need to be changed and possibly some discussionable stuff in this question.

Right, what I want to achieve (in the name of improved performance) is to make settlements, such as Minor City/Large City/Huge City look exactly like a large town, as this is the highest level town I can play siege battles smoothly under with everything off or lowest in configs.

At the same time, I want to aim for the walls, towers and gates to be as strong as in the actual settlements (which probably means I should just leave descr_walls untouched?)

I'm not quite sure how to achieve that, but it looks like descr_building_effects has something to do with it.

Similarly, I want to make fortresses and citadels look like castles (yes it robs a bit of challenge but at least that would mean I don't have to autoresolve).

Alternatively, I'm thinking of just making the normal houses (i.e. the ambient buildings) not show up on the battlemap or replace them with say a any-color cube that has the rough outline (but of course drains way less performance) In this case i'm guessing I would have to replace a few tga or so, but again I don't know which ones.

Has anyone done this kind of modding before and/or do you know how to do this? If everyone would input what little (or much!) they know, I'm sure we could figure it out. :)

This should more or less cover what you want to do:
http://www.twcenter.net/forums/showthread.php?t=91758

Moved to modding questions.

You really had to force me to register at TWC didn't you? :p

Oh well, I did and posted my question in the same topic. Maybe you can help ? :D