I also have the similar problem. I have 2 realms on the same computer with 2GB ram running Ubuntu server 9.04. Server is only for me and my friends, there are never more then 10 players online, so don't mind the configuration. Anyway when realms are started at the beginning they take about 400-500 MB (with vmaps on and grid unload on). As the time goes by both realms grow in memory untill both take about 1GB (1 can be 700MB, other one 1400MB it doesn't matter, the point is they fill out the memory), then one realm dies, and if the restarter is turned off other one continues to grow until he takes about 2GB of memory, then it dies too. I've noticed that sometimes it take more than a day for both realms to fill up the memory and crash, sometimes they crash 2 times per day with same number of players online. I am now using rev 7721, but it happened before too.