For some reason a world run on a mac lags terribly when the player loads a chunk with about 100 spawners. The spawners are a mix of block and minecart spawners but run fine in single player and PC direct connect. The spawners will sit there and dont spawn anything until a button is pressed. The spawner search radius is the max of a short variable however. The three pinpoints could be search range, spawner minecarts, or spawners in general. The server is run with 2GB RAM on a mac and any other world runs fine. Not sure about Mac SSP.