Norton isn't that bad of a resource hog. It's not a big deal.
It's not a very good antivirus program (because virus writers often write viruses specifically targeting Norman because of its high profile), it's really annoying about reminding you to pay them, and it's a real pain in the butt to uninstall. But with it installed and paid for, it works pretty well and it's nothing to worry about.
Just don't renew it again
BTW, if you want to make it run a little more smoothly, you can disable the realtime protection elements. If you do this, be sure to use your head while using your computer, use a browser other than Internet Explorer, and make Norton run scheduled full system scans daily/nightly. You'll be fine.