This is our configuration for jboss servers you can try it out We did load testing on different combination of cconfiguration, this turns out to be the best performance. JAVA_OPTS="-d64 -server -XX:PermSize=2048m -XX:MaxPermSize=2048m -Xms4096m -Xmx4096m -XX:+UseParallelGC -XX:SurvivorRatio=16 -XX:ThreadStackSize=512k -XX:NewSiz e=2048m -XX:MaxNewSize=2048m -Dsun.rmi.dgc.client.gcInterval=3600000 -Dsun.rmi.dgc.server.gcInterval=3600000" The config will reserve 6GB for jboss. My app usually use up 3GB. Let me know if this is helpful, or any questions. Env. Solaris 10. 64bits 8GB phsyical 7200RPM 200GB HD. 4 core View the original post : http://www.jboss.org/index.html?module=bb&op=viewtopic&p=4247086#... Reply to the post : http://www.jboss.org/index.html?module=bb&op=posting&mode=reply&a...