@someoneyoulike yes, you can block other users: in this page

@someoneyoulike We have set up instances where the db is not on the same machine as the server (mostly for horizontal scaling purposes, etc.) We don't notice any real-world degradation of performance. MongoDB is plenty fast, it's almost never the database (or network connections to the db) that are the bottleneck. Unless your app server is in Toronto and your database is in Singapore... but then you have other problems