gl_cull
This variable toggles the use of internal OpenGL functions for removing covered objects. When this variable is set to "1" the game will depend on the OpenGL driver to use it's culling functions to remove certain objects from the calculations because they are covered up and would not be seen anyways. It is a good idea to leave this toggle enabled because it will increase rendering performance.
Use the OpenGL driver's culling functions.
Do not use culling to increase rendering performance.