james mckay dot net
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Do antivirus scans really need to brick your computer?

Pretty much every antivirus software package that I have ever used has a really annoying flaw. Whenever it launches into a full system scan, it slows your computer down so much that it hardly even responds to your keyboard and mouse. Given that a typical PC has up to half a million files knocking around on the hard disk, such a scan takes a good couple of hours at least.

It seems that when they perform a scan, they process the files back to back, which results in a lot of churning of your hard disk as the heads continually seek all over the place to find the next one. The fact that they’re both processor intensive (with fairly complex heuristics and pattern matching algorithms) and hard disk intensive means that during this time, they effectively brick your PC for a good two hours or so.

I’d have thought it would be fairly easy for them to fix this, by introducing a pause between each file (or each chunk of a file, for larger files) to give your computer a chance to respond to user input in a timely fashion. They could go in to a fast mode if you were running a screensaver, but while you’re actually trying to get some work done, you really want them to ease off the gas.

Unfortunately, I’ve not yet come across any antivirus programs that do this. Why not?


  • # Reply from delboy at 21:11 on 5 Dec 2008

    Using AVG free on a dual core Intel 2.2Ghz on Vista, is fine here. Less than half of each core is being used. No noticeable slowdown at all. Furthermore, AVG scans all downloads so as to catch any maliciousness before it gets a chance to do any damage.

    I’ve used AVG for many years and have never had a virus related problem.

    Maybe you should get a better virus scanner, a faster computer, or an Operating System that doesn’t even need a virus scanner…

  • # Reply from James at 21:53 on 5 Dec 2008

    Yes, I’m using AVG Free too at home. Most of the time it’s fine, it’s just when the scheduled scan kicks in that it gets painful. I always end up cancelling it as soon as it starts.

  • # Reply from David at 00:31 on 6 Dec 2008

    Hey James, accidentally came by your blog and thought I would leave you with a presie.

    NOD32 is your answer. It’s always actively scanning your PC ( no need for full scans, doesn’t even schedule them ) and you never see it. It’s the best AV out there. True, it may take some time to get used to it ( it isn’t exactly computer-idiot friendly ) but it does the job perfectly. Read up on it and purchase it. I promise you wont be disappointed.

  • # Reply from Antonio at 12:59 on 18 Dec 2008

    Hi everyone!

    I have tested AVG Free, Avast, NOD32, among others… but no one was “nicer” enough for my Pentium 3 1GHz computer (yes, I know, my system is quite old, but is useful for my needs)… The best I have tested is my current anti-virus: Avira Antivir Personal. It is not as full featured as the others but has a real time scanner, anti-rootkit, anti-spyware. It’s all that I need. It lacks the “email scanner” but I use webmail most of the time and my messaging software is configured not to open attachments automatically.

    About choosing an operative system that doesn’t need a virus scanner… sorry to disagree but every OS needs an AV scanner, may be not an “active” or “proactive” one but it is a matter of responsibility with your friends, family and co-workers. Imagine you use a “virus free” OS, then you receive a PDF with a virus… ok, your OS is not affected but, what happens if it is a really good PDF and you send it to a friend and he/she opens it trusting the sender?

    Good blog James! And thanks for the “Comment Timeout” plugin for WordPress! I’m really loving it!

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