"david.lloyd(a)jboss.com" wrote : Do any of these changes have negative performance implications? For example it looked like the changes for JBCL-128 might introduce some significant overhead. Might be worth doing some before/after profiling just in case? It's only got extra overhead if you install a handler and then it depends upon what the handler does. I assume the one you are talking about is the ClassFoundHandler. The only additional processing for no handlers are a few list == null checks at the policy, domain and system levels. The use case we are going to implement is for the Lazy Activation feature in OSGi. In that case, you install a handler when you create the classloader, but then remove it once the first class is loaded. So there is only overhead for one classloading request and that is to implement the desired feature - i.e. start the services associated with deployment. View the original post : http://www.jboss.org/index.html?module=bb&op=viewtopic&p=4266516#... Reply to the post : http://www.jboss.org/index.html?module=bb&op=posting&mode=reply&a...