No offence but don't comment on things you don't know the answer too... Norton is one of the lightest AVs out there.
Sorry to say but Norton sucks. I have never in all my years had a program turn on me when the subscription ran out, I did used it some years ago. They actually expect me to hand over more money for this anti-virus turned malware they are crazy.
Also with Norton I had to disable it half the time to download files that I needed to download. Yeah Norton has changed over the years like the very old ones used allot of resources usage now it doesn't and it improves the system by keeping the bad out and good in.