WebSphere Message Broker uses the state-of-the-art technologies for executing java code to provide very high performance at the runtime.
Especially when you are configuring the broker for debugging.
Once a debug port has been configured on an execution group, the AOT compiler is disabled which impacts quite heavily on the performance.
This configuration stay even if you have not attached a debugger to the execution group.
If you need to reach the highest performance never forget to disable the debug port. I typically set the port to "0" which disable it.
The debug port can be disabled through the CMP API (using the API execiser) or using the MBExplorer (MBX). With MBX, right click on the execution group and select "Flow Debug Port":
I have recently made a project where 200 MB files had to be decrypted and the signature of the files validated. By removing the deactivating the debug port, the performance was improved 10 times !!
In summary: don't forget to disable the debug port when doing performance tests.