My first though was: "I could make a game with this". And the first thing on my todo-list would be "server rendering", so that the server only send the client what the player see.
There's also not really a lot of benefit to doing something like this. Maybe you run better on computers that have worse graphics cards (and I don't actually think you will), but you'll run worse on computers with worse internet connections. You also are now spending a lot more on servers because every player needs a nontrivial portion of a server machine.
If you have any kind of multiplayer game: It would make cheating harder, and make some kind of cheats impossible.
The real solution would probably be finding an effective way of dealing with memory on the client side. I don't know what the state of the art in javascript land is but big environments like this are better streamed from disk into memory portion by portion rather than putting it there all at once (i'm pretty sure there is no standard api that lets you do something like this).
You keep track of all the points the player is currently looking at, and sort them. Then when the world state is updated, the server check all clients whether to send the new update or not.