I was thinking about @LucasFIN : talking about street modules. Wasn't sure if it was merely a hand design proposition or some generated module like the NPC villages that are automaticcaly generated by Minecraft.
I used to make a lot of modding, before CraftBukkit was really a thing and got integrated in Mojang's studio. Problem is: you have to make the players download your own version of MC (meddling with player hearts and inventory did not allow any plug-in unfortunately ^^).
I remember we had quite a few problems at a time with the map being too big and making occasionally crash the server after some time. The solution was to set a "invisible wall" on a new map that delimited the boundaries. This last one was still very big though.
Oh well, I guess Minecraft have solved since then a few of their memory / optimization problem ... I hope