Hi,
Are you saying that you are testing monitoring capabilities using the Javaagent and epagent separately? Can you provide more details please?
Also, we don't have a sizing calculator for the agent, if you add a custom instrumentation you need to validate this in a QA test environment before moving it to Production, even after that, you might require to perform additional tuning of the instrumentation.
If you still have a concern, I suggest you to open a case with support.
I hope this helps,
Regards,
Sergio