bind _addr specifies the address to bind to for incoming communications. mcast_addr and mcast_port specify the muticast address/port to use when broadcasting messages to the cluster. Even if you don't specify a mcast address and port one is used. See the javadocs on the UDP protocol on the JGroups website for defaults. There is no specific reason why specifying these would help performance though. I suppose what you need to do is to identify where your bottlenecks are - at what stages of the app do you run into performance bottlenecks, etc etc. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4061410#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...