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Conclusion: A Pleasant Surprise

Do Virus Scanners Slow Down Your System?
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As mentioned on the first page, I came into this story idea aware that I had a prejudiced expectation. Although I’d never actually tested it for myself, I was under the impression that the presence of a resident virus scanner would have an adverse effect on system performance.

I’m very happy to report that my preconceptions have no place in today’s PC world, as even single-core processors are able to demonstrate comparable performance with or without modern security software installed. This is true not only for basic virus scanners, but also for comprehensive security suites.

Having said that, it’s also true that the presence of security software isn’t undetectable in all circumstances. We do see an increase in application launch times with a virus scanner installed, but the only significant wait time is a couple seconds added on the first launch of a program. Subsequent launches appear to be cached, and the wait time is almost imperceptible.

The only benchmark that shows a notable performance decrease with a virus scanner installed is PCMark’s productivity suite. Even here the performance hit is only notable with two of the 10 tested security products, and in this case, an increase in Windows Contacts search times is the main cause. While I can’t speak for everyone I know, I do not spend a significant amount of time searching Windows Contacts, so for me this isn’t much of an issue.

While these results are encouraging, a couple of questions need to be answered. As we mentioned at the beginning, we’ve limited our testing to performance with the virus scanner installed. However, what is the performance hit during an actual virus scan? This is something we hope to examine in a follow-up review in the near future.

However, for the time being, we’ve learned that a user can confidently install a virus scanner or Internet security suite without being too concerned about performance consequences. It appears that typical tasks we undertake when using our PCs will not be notably slowed by the security software on which we rely. In the end, I’m pleased to admit that my expectation of a decrease in general PC performance when a virus scanner is installed was incorrect and obsolete.

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Top Comments
  • 38 Hide
    Hupiscratch , November 30, 2010 6:44 AM
    I think Microsoft Security Essentials should be included if possible and there is a situation that I think it is greatly affected by anti-virus software: Windows start-up.
  • 32 Hide
    aznshinobi , November 30, 2010 5:48 AM
    Avast please?
  • 24 Hide
    apache_lives , November 30, 2010 6:31 AM
    this is tested on a fresh install - the average system has a ~2 year old install and fragmentation and lower end hdd's, combind with a crapload of other software trying to startup - no really a real world benchmark.
Other Comments
  • 5 Hide
    theshonen8899 , November 30, 2010 5:30 AM
    Great article, thanks!
  • 24 Hide
    iam2thecrowe , November 30, 2010 5:31 AM
    before i read the article, my guess is Norton is the slowest and most useless....
  • 24 Hide
    tony singh , November 30, 2010 5:41 AM
    How can u forget Avira , it's so popular & so good .
  • -3 Hide
    alyoshka , November 30, 2010 5:43 AM
    I guess the new ones are lighter than the earlier ones for some of them....
  • 4 Hide
    ruffopurititiwang , November 30, 2010 5:45 AM
    This is the kind of article that keeps me coming back to Tom's! Kudos!
  • 32 Hide
    aznshinobi , November 30, 2010 5:48 AM
    Avast please?
  • 4 Hide
    micr0be , November 30, 2010 5:49 AM
    talk about heavy modifications on the new set of AVs compared to the older ones ... my surprise is norton which i was expecting to cripple the system to a halt .... very nice article btw
  • 2 Hide
    tony singh , November 30, 2010 6:00 AM
    @Fip - Because when dirty viruses do their job, you'll get a headache.
  • 13 Hide
    iam2thecrowe , November 30, 2010 6:05 AM
    iam2thecrowebefore i read the article, my guess is Norton is the slowest and most useless....

    well i am really surprised
  • 2 Hide
    takeapieandrun , November 30, 2010 6:24 AM
    iam2thecrowewell i am really surprised

    I get Norton Security Suite free with Comcast. I was kind of bummed when I found out that's all they have available, but so far its been good to me. I haven't noticed any adverse effects, maybe startup is s little slower.
  • 24 Hide
    apache_lives , November 30, 2010 6:31 AM
    this is tested on a fresh install - the average system has a ~2 year old install and fragmentation and lower end hdd's, combind with a crapload of other software trying to startup - no really a real world benchmark.
  • 9 Hide
    Anonymous , November 30, 2010 6:31 AM
    it would have been useful to see a difference in the benchmarks using different HDDs like the 5400 RPM laptop ones, 7200 RPM and SSDs, that would have made a difference
  • 4 Hide
    Anonymous , November 30, 2010 6:43 AM
    Well the biggest slowdown you will experience with antivirus software is when you open a folder full of exe files and explorer tries to show all the icons of the executables. There is a very noticeable slowdown in that case.
    Also i would have liked a startup benchmark, because the antivirus also slowdowns somewhat the startup process.
  • 38 Hide
    Hupiscratch , November 30, 2010 6:44 AM
    I think Microsoft Security Essentials should be included if possible and there is a situation that I think it is greatly affected by anti-virus software: Windows start-up.
  • 5 Hide
    cjl , November 30, 2010 6:58 AM
    iam2thecrowewell i am really surprised

    Norton has VASTLY improved compared to what it used to be. I use Norton 360, and I have to say that it has been a great product.
  • -7 Hide
    Anonymous , November 30, 2010 7:04 AM
    2 ddragoonss
    thanks,
    AV is far from 100% protection, and could bring new problems (recently ESET NOD Smart Security causes problem with internet connection due to connection inspection / filtering ... ) For IT Pro is risk to get a virus very low, and if get one - few hours to get it out is worh instead of years of boring my pc with AV software
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