Not exactly sure of your AV situation but here are a few thoughts:
It sounds like your real-time security scanner(s) are causing the problem.
Only run one AV solution. Multiple AV's do not play well together...they hunt each other and in general do the "Don Quixote thing"
They also devour system resources.
Norton Anti-Virus has a reputation as being the king of resource-devouring AV solutions....I urge you to get rid of it.
I use the free version of AVG and it is excellent. Folks also rave about Avast!...another free AV solution.
A great free program for managing this sort of thing is WinPatrol. I have it set to manual and use it when needed. Download it, launch it, and it will identify running processes, startup apps etc. And it will do many other things as well.
When I say "free", I should say "donation ware", it's all very, very good.