mhagain:
You understood me bad - I am loading from .obj just initially after I model some thing in Cinema4D and export it. Then I have a function in my engine that already saves a map in my own format, which saves every number as bytes, plus there is also space partitioning saved in that file. I dont know what exactly you mean with memory-mapping a file, but from name it sounds that it would only work for static arrays of classes, and not for linear linked list of dynamically allocated classes as I have. I like .obj cause its intuitive and readable and there is no reverse engineering about format specification.
PVS are really good idea, I like it. I will definitely try it. I am thinking of making special class for that, which is some box area and list of other box areas that are potentially visible. In map editor, the user will choose these manually so there will be no need to make some extra complicated code that determines what is visible from where (even if THIS is exactly the point where occlussion culling would be useful...) and also no need to compile a map like this after every change.