World generation is functional and even cross-compatible with the singleplayer. That means you can take a singleplayer world into multiplayer and back if you wanted to! Aside from that lovely feature the world generation is VERY fast. As you can see below... The speeds will vary based on the biome mod files used of course but they will likely never go beyond 5ms per chunk.
The server is also VERY capable in terms of world capacity. I would be blown away if a server could fit more clients than required world space onto a server. Assuming clients aren't too heavy for a server I would expect to see servers that are 512x512 chunks running on low end machines such as tablets.
I also setup mod verification for client to server connection. What this means is that users who modify a mod pack will be unable to connect to a server that doesn't have the exact same files. Even a single number changed will result in a mod mismatch error. This is just a first step in anti-cheat for Project Explore but a big one nonetheless. This is not to say there aren't workarounds but this will definitely prevent easy cheating.
Lastly I implemented a new server command! kick_user which can be used to well... kick users of course! It is already working perfectly which is a good sign.
I hope that things keep moving at this rate. If they do I just might have multiplayer up and running for users in the next stable build. However I can make no promises!