I have been using AVG for a couple of years now and have not had any virus since I started using it. Previously I had McAfee for 4 years and had occasional viruses. I think I will stay with a demonstrated effective product. And it is free.
I have noticed that while AVG is scanning, my PC seems to come to a crawl.
I don’t know but there is a related comment or two following yours.
I use AVG on some of the machines. In my past experience (They may have improved it) McAfeee may as well be a virus. That's why schools and GIVE it away free. The bloated mess of Norton, which was once a good name, is not much better, in our experience.