As far as I understood it, in the webGL renderer, anything present in the layout view of the current layout has their textures loaded, if an object is created without his texture currently loaded, it will be loaded on the fly, then at the end of the layout, everything not needed anymore will be unloaded from memory.
That may be a wrong or incomplete interpretation, but basically: C2 is meant to take care of loading and unloading textures for you.