I think it will depend heavily on the kind of traffic that you are generating. If performance is critical, you ultimately may need to conduct some experiments with simulated workloads and measure performance.
I'm not sure what you mean by "real-time messaging", but you will never get real-time anything on a PC. If you need real-time messaging, you need a real-time OS like VxWorks.
CCR has the added built-in ability to remote messages across process and across machines. If by "internal messaging" you mean in-process, you may find that CCR is more complex than you need.
-G