If you want to get a better understanding of the CPU usage of the OMEGAMON address spaces running on z/OS, there are a variety of techniques. I've blogged extensively on the topic of OMEGAMON cost of monitoring considerations in prior posts.
Let's say you are looking at a particular OMEGAMON task, and would like to know more about what that particular task is doing. There are some useful commands available to help better understand OMEGAMON CPU usage (such as the PEEK command).
Here's a link to a document that shows examples of some of these commands and how to use them: