Thanks for responding!
I'm talking about dividing the map into multiple channels so that users only receives updates from those around them, and hopefully make it more responsive.
So for 1000x1000 areas, if I'm at "x":3033521.3,"y":-3025356.4, my client subscribes to /xkcd_x3033_y-3025
And adjoining area/channels if they're close to a border. (but only sends updates to the current area/channel.)
...IF it's easy enough for the client to dynamically change channels, and be subscribed to multiple (up to 4) channels.
Then combine this with multiple spawn locations at other interesting locations when demand is high. But they can still explore and meet others.
So it should more responsive and less data sent than everyone getting updates from everyone.