Sorry, I never looked at the subject line. I suggest you also set -Xms1300m. This will set the min and max heap to the same size (as it is, you are probably getting an initial heap of 64m, with the JVM constantly asking the OS for more). This will also prevent you from getting "out of memory" errors if the JVM asks the OS for more memory and the OS refuses to allocate it. Also, try running with -verbose:gc set, this should show you the amounts of heap in use before and after each garbage collection. Relying on the OS to tell you about the JVMs memeory usage is usually not too helpful. Also, I hope that you have at least 2GB of RAM on your machine. Otherwise you might not be able to get a 1.3GB heap. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4118799#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...