ok, well, i dont have a normal color skin, i have a very nice looking dirt filter applied to the whole szene combined with ambient occlusion and some unregular noise-textures mixed to that. so there is a lot of details in the texture which cant be reproduced this simple. and if i use a shader to reproduce it (would be possible) but i think that it wouldn't be faster in the end because of those multiple lookups i'd have to do

maybe i will try to do something like what octree would do and split my big city into a bunch of parts (say 8 subparts which would by themself be built up of those 11 parts) thus i could gain speed and go down to a size of 1024x1024. sounds fair??