I have some doubts when it comes to using either texture on a map that doesn't have 3D skyboxes (the use of a sky_camera entity). For some reason, I've always thought that using the regular skybox texture would, sort of, 'prepare' the map for possible external skyboxes, while its '2D' variant would ensure that no external skyboxes are ever rendered. However, I may be wrong and I'm in fact rooting for the '2D' one to simply disable sky_camera projectations on specific areas. In short: should I use the regular skybox texture even if there are no existing sky_camera entities in the map? An example of performance/visibility changes between two tool textures would be the use of a "PlayerClip" and "Invisible" textures.