Do Antivirus Suites Impact Your PC's Performance?

Most of us are now fairly confident that our antivirus scanners are doing their main job of protecting our systems from malicious pests. But what are those scanners doing to system performance behind the scenes? Are some scanners better than others?

Let’s start with the good news: antivirus products all work. If what you care about is protecting your system from viruses and similar digital pathogens, just about every major vendor in the AV space does a respectable job. But don’t take my word for it. Check out AV-Comparatives, which currently evaluates 20 of today’s most recognized names in the antivirus world.

The above chart shows AV-C’s results for August 2011. Now compare against the same tests done in August 2010.

While it’s interesting that the three top performers on these charts are consistent, the point is that most players can change considerably from year to year, and even month to month. Does anyone really think that Microsoft went from 98% accuracy in 2010 to 92.5% and stayed there? As if the company suddenly forgot how to write virus definitions? No. Quite literally, sometimes AV companies have bad days. In the 2011 AV-C tests, Sophos and Webroot (which uses Sophos technology) were the only vendors to be dropped from the testing because the cloud-based portion of Sophos’ definition set was down.

As multiple vendors agreed in interviews with us, when it comes to detection and isolation of modern viruses, worms, bots, and so on, just about everyone does at least an adequate job.

“Most of us are close,” says Dodi Glenn, product manager at Vipre Antivirus. “The thing is, you could say that you detected some sample set, and your AV is better than mine. But if you fast forward, I could say that you missed X, Y, and Z. There’s a notion of when you gathered the data. And is it a zero-day? Has it never been seen before? Is it a proactive or reactive type of detection? It all depends on the sample set you’re using. In theory, your efficacy rate is going to change any time you update.”

Accuracy may no longer a primary criterion for product selection, although it should still be considered as a secondary item after pricing and full AV suite functionality. There is another side to consider with AV products, though, and long-time Tom's Hardware readers know it well. What impact is the software having on your system? Loads of features and stunning detection accuracy may be impressive, but if the background AV product is sucking minutes or hours of your productivity and performance away from foreground tasks, you have a problem. In general, for reasons we’ll discuss soon, we are less concerned about the impact of scheduled scans than we are about the low-level monitoring that today’s AV products perform constantly. Will they slow your gaming? Will they balloon your Web page load times?

We don’t need an exhaustive answer from examining two dozen names. We figured that half of a dozen would do for establishing whether or not AV products in general are dragging on your system and if there is a significant variance in this drag between products.

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  • dogman_1234
    Regardless what anyone says: Using McAfee is like using a Glad garbage bag as a condom.
  • Martell77
    I've been using Trend Micros AV since y2k and haven't had a reason to switch. Because of the systems my clients have I never recommend Norton or McAfee and if they have it I always recemmend they switch. Its truely amazing how the performance of their systems increases after getting rid of those AVs, especially Norton.
  • soccerdocks
    On the scanning time page there is an error in the second graph. It also says first run.

    Also, the timing of this article was excellent. I had just been doing some research about what anti-virus software I should switch to, mainly based on performance, but I guess I just got all the information I needed.
  • compton
    Some of the results seem mysterious, like all the times the no-AV configuration scored lower in many tests than it should be faster in. Is it possible that using the Wildfire as the system drive instead of the platter would have eliminated this behavior? In general, I hope there is a second part to this that does include SSD runs. I would think any advantage AV products have vs. the no-AV config would evaporate.

    I stopped using AV products on my personal systems back in 2003. Norton back then was god-awful on a Pentium 4 systems, seemingly crushing the life out of a system. Even with a first generation WD Raptor 36GB my P4 2.6 would choke not only with Norton, but also McAfee. I might not use AV software, but I do put it on my family members' systems when it doesn't kill performance. In that respect these modern solutions seem much better.
  • ChiefTexas_82
    On my Pentium D I have to run McAfee when I'm gone for a good while or sleeping as my computer slows to a crawl during the scan. Even bringing up the menus to stop the scan take way too long.
  • darkstar845
    Why didn't they test this on a computer with average specs? The 8gb ram and very fast CPU might be offsetting the impact that the AVs put on the computer.
  • bit_user
    Thanks for this. I remember the bad old days when AV could make software builds take several times longer.
  • cdhollan
    While my comment is completely tangential, but my inner chemical engineer can't resist making a small correction in what is otherwise a great article:

    >>Apparently, this is somewhat like saying you can boil water at 230 degrees Fahrenheit instead of 260 degrees. As long as the water is at 212 degrees or higher, no one really cares.
  • rottingsheep
    installing vipre speeds up your computer?
    i think something is wrong with your numbers.
  • Amazed ESET is not being tested considering it sells itself on its performance over the competition while maintaining the same levels of protection.....
  • pharoahhalfdead
    I used Vipre for a couple years bcuz it has such a low memory usage and the firewall. It might not be as good as some others at detecting rootkits or something but on a system like mine quad core 8gb, running 45 process including av to use only 15% memory compared to 22% with pc tools, I'll take this one.
  • pharoahhalfdead
    I've had none of the "install problems" or 20 min downloads for definitions. I just installed windows 7 and only had to reboot once. Each system is different though. I like the 360's variance and more control allowed to the user.
  • joe nate
    The "install" chart baffles me. In addition to application start-up time.

    I had kaspersky on my intel i7-920 system with a SSD app/boot drive, and kaspersky brought my system to it's knees compared to a clean system without any antivirus. It was like a computer from 7 years ago in it's response time. Try to install something? Took 10 seconds to start the pre-scan, then it would pre-scan and then install was slower. Run firefox from a fresh boot? Wait 3 seconds. 3 seconds? With a SSD?

    I removed it and tried out norton internet security and everything is instant like my clean system. I don't even notice that I have it most of the time. I attribute that partially to my good system, but I attribute the other part to it not just adding arbitrary wait times onto everything I try to do. Use that processor! I have multiple more to spare!

    I know people think dirty of Norton, but as long as it protects me while pretty much being invisible to my performance to the naked eye, I'll give the once slow kid in the class if he's a genius now. I don't know why, but it works.
  • beavermml
    please test the effect on lower end pc like netbook , etc... many users who are using those pcs are not nerdy like us who bought i7 + 8GB ram.. even i dont install AV in my pc for maximum performance
  • SteelCity1981
    AVG Free is pretty decent I use it and the performance that it displayed on this site is even a bigger plus to have it if you are looking for a decent anti-virus that's free.
  • carvedinside
    Sometimes these AV suites don't cleanup all their files in the system when uninstalling ( I know Kaspersky does this). You need to use the standalone removals. Maybe this is why the results are so screwed up, cause a system with no anti-virus is ALWAYS faster that a system with.

    Tom's something is wrong with your test bench.

    If anyone is interested, I did ran my own tests for most of the latest security suites and have reached to the conclusion that Avast 6 is the fastest around. A scan on 10 GB of data on an SSD took ~2 minutes , compared to 8 minutes it that took Kaspersky to finish the same job.
  • purrcatian
    Avira consistently had some of the best detection rates. It is also free. Why wasn't this obvious choice tested?
  • chumly
    Every time I've ever gotten a virus on a computer that ended up having me reinstall Windows, Norton was installed. That was also about 3 years ago or more. Since Windows 7, I haven't had any problems with viruses at all, and to give people here advice: if you paid for Windows, you may as well use the virus scanner that they give you free with your product instead of spending more money.
  • Scotty99
    Is avast not a popular AV anymore? The only time i see it in this review is the front page, where it ranks in the middle. I like avast because of the chicks voice "Avast has been updated" or whatever she says hehe.
  • Nice article, however it's really hard to benchmark something like this. Good try though!
    I agree that Avira free should have also been included to balance the field a little bit.
  • Vladislaus
    These kinds of tests shouldn't be made using almost top of the line hardware. Just take a look at the processor, it's the fastest desktop cpu from intel on sale. Mos people don't have a computer with that kind of processor. Why not do the same test with an i3 or an lower end i5?
  • gondor
    What kind of feedback did you guys expect from companies that give away free AV products ? I mean it was you doing the testing, independently ? This should be no different from a random Joe User who downloads AV of choice and sets it up so you should have included both Avira and Avast! in your test.
  • wildkitten
    I'm not sure why people still blast Norton. To me it shows they really haven't done any looking or researching on their own and just go by popular opinion.

    Yes, it is very true that few years ago Norton was totally awful at hogging system resources. But 3 or 4 years ago they corrected it. I have been using their Internet Security suite for 3 years now and I can't hardly tell any affect on my system. But of course as the author says, with modern processors, none of them really show a strain on the system. But I have had zero issues in the three years since I have returned to Norton. I am sure that many of the other AV packages are good as well, but this constant Norton bashing by some just seems to show ignorance.
  • DavC
    It would be nice if someone could spend some time re-running these tests on a netbook or typical 2-3 year old laptop. Not only will the performance penalty will be far more obvious on lower powered hardware, it is the place where it is most important!

    I would have also liked to see NOD32 in that line up!