If you bring up your virtual server, but do not bring up JBossAS, how much free physical memory do you have? That is the maximum you should set the Java heap. On my Server 2003 system, which has 1024MB RAM, I have 550MB free, which suggest to me that you have very little free RAM. Also, is MySQL running on the same virtual system? If so, it also eats up quite a bit of RAM I imagine that you are thrashing your memory. If you plan to run both MySQL and JBossAS on the same system I would not go below 2GB of RAM. If you run them on separate systems, 1GB for each system. Your full GC to total GC ratio is very low, which is good, and makes me assume that your heap settings are good for your application. A detailed analysis of the gc data might offer some suggestions for improvement. See my presentation at http://www.cecmg.de/doc/tagung_2007/agenda07/24-mai/2b3-peter-johnson/ind... The number of threads has more to do with the number of connections made. If you mean Java threads, then this represents the number of simultaneous HTTP connections. If you mean MySQL threads, then this depends on the number of database connections made, and the settings for the database connection pool. We have gotten very good performance using JBossAS 4.0.2 and MySQL 4.1. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4142506#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...