- never use CSG-Subtract
- if you use bsp-tree make sure that you cannot see nearly the whole level from one perspectiv (frame rate would go down)
- if you have to have a big area with blocks, consider to use fog
- special level details like pipes, machines, wires etc. should be made as a) models or b) sprites (wires hanging from the ceiling)
- when you have completed building one part of a level (or the whole) and it comes to texturing, load a simple texture (complete black or white for example) into your wad and set its none flag.
Then assign this textures to all the blocks you'll texture.
After doing so you start selecting the blocks and surfaces which will be visible and assign a texture to them.
The none-flag on all other non-visible surfaces will tell the engine not to render these, so you might get a few more frames per second in the end.