You need to provide some actual information, any program loaded into memory will slow down a PC.
All the time or just at certain times ( bootup, DAT updates , policy enforcements etc)
The whole system or just certain Apps
Basic VSE or do you have plugins and other Mcafee products running like ASPW or HIPS
What is the basic PC spec and OS patch
What is the general resource usage in memory and CPU at rest
How do you have configured the OAS settings and artemis
What exceptions do you have set