In my opinion the default value of 5 is pretty low for Cloudtrail logs, specially if it is an organization trail, I was having some lag in the ingestion and started changing this until I got to real time data without impacting the Agent.
One issue with the cloudtrail logs is that the agent needs to parse each message to split the records field in multiple events and this will impact in the performance as well.
My suggestion is to change the max_number_of_messages to see if you can increase the event rate, and if you reach any plateau after that, scale horizontally with another agent.