The scene have no optimations and the engine offers only LOD until now.
So all the culling process is done by Gfx-Card processor.
If for scene optimization you mean Octrees or BSP , this topic has been widely discussed on their forum
They claim that these are outdated techniques
Modern graphic cards can render milion tris ,it does not worth while anymore wasting CPU cycles for Octrees \ bsp
Modern game engine use zones / portals / paged geometries along with LOD
