Norton? Ugh, the only good thing they make is Symantec Anti-Virus Corporate Edition.
Typically Norton is a huge drain on resources, I would personally find a program that cleans up Norton (some times Norton doesn't even have an uninstall and even when it does it only does it badly). Then find a better Virus Scanner, if you have a router don't bother with a firewall, hardware firewalls are far better than software ones.