For performance tips regarding collisions:
Usually you will want ellipsoid to polygon collisions set up between your 'characters' and your level. Rather than use the level itself as the collision mesh, make a low polygon mesh which can be used as the collision mesh with entityalpha set to zero so that the collision mesh is not rendered but allows for quick collision detection.
Usually you will want ellipsoid to polygon collisions set up between your 'characters' and your level. Rather than use the level itself as the collision mesh, make a low polygon mesh which can be used as the collision mesh with entityalpha set to zero so that the collision mesh is not rendered but allows for quick collision detection.