Hello,
Could you please let us know -
1) What version of SEP are you using?
2) What Server OS are you running the SEPM on?
3) What other roles is this server carrying other than being a SEPM server?
I would recommend you to check this Document -
Symantec Endpoint Protection Sizing and Scalability Best Practices White Paper
http://www.symantec.com/docs/DOC4448
Hope that helps!!