We switch our application server from JBoss4.2 to wildfly9.0.1 recently. After some testing, we found the JMX call performance degrade a lot.
Take following test method as example, we use it to send one string array, the array size can vary, and each string length can change.
public void perfWithStringArray(String[] events)
The client and the MBean server are located in the same machine. Please take a look at the performance data

The last two columns mean how many event could be handled in one second. You can see the performance degrades a lot.