JBossWSInvoker::invoke calls ApacheCXF AbstractJAXWSMethodInvoker::adjustMethodAndParams which checks for the existence of @UseAsyncMethod annotation on the method to be invoked. That is expensive and not needed at all if that annotation is not used (it's a cxf specific one..).
We should avoid doing the check if we already know from the Jandex index that there's not such annotation in the deployment.