Hello,
What version of SEP 12.1 are you running?
How much RAM are these Laptops have?
User can disable many auto scan,such as startup scan,active scan when new definitions arrive,network files scan,to minimize the SEP effect on PC performance.
1. Disable startup scan and active scan when new definitions arrive, go to Virus and Spyware Protection policy-->Administrator-Defined Scans-->Advanced.
2.Disable network files scan,go to Virus and Spyware Protection policy-->Auto-Protect-->Scan details-->Network settings
3.Disable file cache or disable rescan cache when new definitions load,go to Virus and Spyware Protection policy-->Auto-Protect-->Advanced-->file cache
I would also suggest you to follow these Articles below:
Scalability and performance guidelines for the SEPM Server 11.x and 12.1
http://www.symantec.com/docs/TECH156008
Symantec Endpoint Protection Sizing and Scalability Best Practices White Paper
http://www.symantec.com/docs/DOC4448
Hope that helps!!!