I have discovered strange thing, which possibly will be a big problem when my app goes into production. I have started JBoss server with my JSF app and left it for 3 days for small group of users. Usually it holds not more than 400MB, when I have looked today, it was about 650MB. Application has had slow response times, I had even reports of "service temporarily unavailable" errors. I took JProbe and try to find leaks, but until now I can't. Application is not using more than 200MB, GC runs frequently reducing amount to about 170-180MB. What can I do more about it? Any JVM settings could come to help?