Don't mean to carry this on as an "argument" (indeed I think we agree on some of the issue), but it gets back to what you said about novices versus veterans. For novices, I do think that running a real time scan while they're on line is appropriate, especially since they're prone to clicking indiscriminately. For example, a lot of novices think that whitehouse.com is the Whitehouse site. Whitehouse.com is a porno site (with the usual malware that will infect a machine with scripts just by clicking on a link), whitehouse.GOV is the actual Whitehouse site.
Even experienced users, and I consider myself an intermediate, run with a real time AV scan . . . I myself do. Nevertheless, your points about downloading (which novices also do indiscriminately) and Active X are valid . . . it's just that I don't think a novice does what you say about Active X, plus real time AV for experienced users is just another thing that may enhance security.
Ultimately, though, I agree with your point about comfort level.
Haven't read that article yet, but it sounds like it's stating the obvious: most AV programs slow things down. But IMHO a performance hit is a small price to pay for the essential security of an AV program. Now I'm sure Norton and McAfee are two of the biggest performance hitters, and AVG and Avast have secured a rep for being easy on resources. However, if you look at my post on page 1 of this thread, you'll see that I use, and have used for the past 15 years, McAfee. Had I ever noticed an unbearable performance hit with McAfee, I would have long since switched . . . but I haven't. That's not to say that on a lot of systems McAfee doesn't make an unbearable performance hit. I'm sure it does . . . but it never has on mine. Plus, I tend to agree with whs . . . what else would your CPU be doing?
Now I know this is heresy for gamers, where the CPU has to work heavily . . . so if I was a gamer, I likely would have an AV program that is easier on the CPU than McAfee.
Which brings me to another conclusion. Your choice of AV program depends in part on the primary use of the system.