The game tracks everything in a database, but does not render anything (except apparently water) until your submarine gets within the render range of the given object, which if you are using high TC in a busy world, you will notice a "hitch" in the display as the game renders stuff. Someone a few years ago had what they thought were the distances - probably based on a dev's statement (long since forgotten in the recesses of my grey matter), and lurker (??) makes a statement about it interfering with the renderings of the different battle scenes if you are in the wrong place in the wrong time, in that your submarine's presence in a scene can prevent groups from rendering when scheduled. I don't remember if he mentions distances in his ReadMe files or not...
