Irrlicht Engine

Ah that's a shame . The only other thing I can suggest is trying the same with any triangle selectors you might be using. Is it definetly the node containing the level mesh that's consuming all your RAM? Good luck solving you problem!

The fourth parameter of addOctreeSceneNode allows you to set the minimum number of polygons needed in each octree node. If you are using the default value (128 polygons) then because your mesh has quite a few polygons, the octree that is generated is going to be quite deep and require a lot of ...

The problem here has its roots in hardware. The reason why the indices are of u16 type is because all but the more recent graphics cards have only a 16bit index buffer. Even if Irrlicht did represent the indices as u32 the chances are that the graphics card won't be capable of receiving a buffer ...