I gave up on Norton and McAffee years ago. They slowed down my computer so much it was like using and abacus. Totally useless. Stuck then with Defender and it worked pretty well since then. I don’t know what I’m going to do after October, frankly.
I always considered McAfee to be a virus, not an antivirus. I run Microsoft Security Essentials on my Win7 box; virus definitions last auto updated today at 8:13 AM with a set sourced at 1:54 AM.
Try Comodo Internal Security. It’s what I use on my Windows 7 installations.