I gave up on McAfee earlier this year after three or four years of gradually deteriorating service. The more they "improved" their product the more problems I had. Towards the end it would take up to ten attempts over two or three days to get an upgrade to complete its download successfully. Also their firewall, as it "improved" caused more and more "bsod's" for my system.
So I moved to AVG and Zone Alarm and everything seems to be going very well. Viruses have been detected and I have no indication of anything that has got past AVG. Also the Zone Alarm firewall pleases me. It warns me of many attempts to reach me and I have not noticed any degradation in performance due to the presence of either of these security measures.