If you are using static lighting on your background (no realtime light effects) then write a shader that only calculates the diffuse combined with the lightmap and does not calculate lighting on the geometry at run time, it will speed things up immensely.
Ah right cheers. Using unique textures would be fine if I can use enough. Do you have any ideas, even a rough estimate, of how many textures I can use per scene? Assuming a worst case scenario I have 4 characters rigged on screen, I'm just using diffuse textures and all textures are 512*512... Thanks again!