Optimizing freeradius for very high loads

Good day. I have freeradius running on a Dual P4 server with 4GB Ram. I am using freeradius to service clients. I require performance of 200tps. I am having a problem where many clients do not get responses for authentication messages. Monitoring my cpu and memory load during busy periods, my cpu max utilization is only 10% used, 90%idle. There is also enough memory. How can I optimize freeradius to increase the tps handling capability ? Thanks Ashwin Gobind �This e-mail is sent on the Terms and Conditions that can be accessed by Clicking on this link http://www.vodacom.co.za/legal/email.jsp "