That's good to know Bill, thanks. The difference with what I'm doing is that it's not a member variable (the map) that is being set lazily, but a populated entry in the map, so we just have to be careful against ConcurrentModificationExceptions. Kev, if you're okay with me not using ConcurrentHashMap (and instead using synchronized as I elaborated on above), let me know. Either way, I'll wait for your word before I commit to the performance workspace and 4.7 CP branch. Thanks. View the original post : http://www.jboss.org/index.html?module=bb&op=viewtopic&p=4269459#... Reply to the post : http://www.jboss.org/index.html?module=bb&op=posting&mode=reply&a...