Minecraft wiki entry for Playing_on_servers, associated text: If you are having a slow device, you may encounter a huge lag strike upon entering the server. Lag happens when there are too much moving beings on the server, and the computer is not advanced enough to calculate lots of movements at once. Lag happens oftener when two (or more) players are far apart from each other. The computer only "cares about" the chunks around you, but not those far away, so forcing the computer to load in separate far locations can mean lag.