CSP has been QA'd to handle 10000 agents per mangement (Tomcat) server. However, if you have really noisy policies that are generating a ton of events, you will need to reduce the amount of agents that talk to each Tomcat server.
Also, plan on failover and stand up enough Tomcat servers so that is one goes down, the other(s) can handle all the traffic.
You can have as many Tomcat servers as you need.