Do Virus Scanners Slow Down Your System?
Table of contents
- 1. The Blame Game
- 2. Test System And Benchmarks
- 3. CPU And Game Benchmarks
- 4. File Access Benchmarks
Does the presence of a virus scanner guarantee reduced performance, or does it have a negligible impact? We test 10 different products to see if you’re unknowingly suffering with security software.
Remember the days of Windows 98, when CPUs ran at triple-digit MHz speeds and slogged along with less than a gigabyte of RAM? Installing a resident program like a virus scanner often meant committing performance suicide. And heaven forbid a scheduled scan start up while you were actually at your desk. Productivity could literally grind to a halt. At least that’s how I remember things through the fog of time.
Today's personal computers are much more powerful than they were a few years ago, so perhaps the notion that an anti-virus application will still have a debilitating effect on performance is obsolete. Still, folks who began using computers after multi-core CPUs and gigabytes of RAM became the norm have likely never used a PC without a virus scanner installed. They'd have no way to relate to the days of running lean and mean to keep speed manageable. Now we have resources to spare. Cores sit idle, waiting for a task to execute, while low prices on memory make 6 GB and 8 GB kits affordable for even mainstream users.
We should make this perfectly clear: while it’s undeniable that an active virus scan can cause a heavy performance burden, what we’re really curious about is whether or not performance is affected when a system scan is not running. Does it take longer to open files when you have a resident virus scanner installed? Does the presence of the software tax CPU resources while you’re running other programs? What kind of tasks are most affected by security products, if any?
When faced with these sorts of questions, it’s only natural that we’d run some tests to unearth the real answers—this is Tom’s Hardware, after all. So let’s look a little deeper into quantifying the anti-virus conundrum.
What Does A Virus Scanner Do?
Before we begin our tests, we should at least consider how virus scanners work so that we can see if the results are in sync with our expectations.
There are two main mechanisms that most virus scanners use in order to keep your system safe: file checking and behavior monitoring.
File checking is by far the most prevalent technique. The idea is simple: the virus scanner examines the files on your PC for known threats, a threat being a signature of code that is associated with a particular virus. Because new viruses are being released all the time, most virus scanners will periodically download updates containing the new threat signatures.
How could file checking affect performance? Typically, a virus scanner will examine files for threat signatures every time a file is written, opened, closed, or emailed, or when a virus scan occurs. It thus makes sense to predict that applications accessing files on a regular basis might be slowed down by anti-virus software. Conversely, programs that don't involve a lot of file access might then remain relatively unaffected by the presence of a virus scanner.
Behavior monitoring is the second technology that anti-virus software employs to identify threats. This is a pre-emptive strategy to deal with viruses that have not yet been identified or added to the threat-signature dictionary. The virus scanner monitors the system for suspicious behavior, such as the alteration of executable files. This virus-prevention technique probably has very little effect on system performance, since suspicious behavior is probably somewhat rare.
That should be enough of a top-down overview to get us started. Let's get on with the tests!
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I'm guessing that the results might have been somewhat less flattering to the security suites if you'd run then on a single-core Atom netbook. Mid to high-end systems can certainly cope with anti-virus software; it's at the bottom end that the pain is felt most sharply.
I thought the athlon chips all had their L3 cache disabled? page 2 says 6mb of L3
Would have been nice to see avg 2011 used rather than the older avg 9.
Also the 2 scanners that showed decresed performance in the pc mark test should have been used with the multi core tests. As this was affected the most it would more likely show reduced single core performance.
Not one of those anti-virus programs/suites have I seen recommended on the forums. Where's the AVG free? Microsoft security essentials? malware bytes?
Would also have been nice to see the tests done on a dual core with 2GB of RAM.
An article with so much potential!
Great so you ignore all the 'better' free AV suites everyone with a slight clue uses and just test the ones that get loaded on as crapware for unsuspecting users. I make a living removing those very suites.
Way to miss the point for the people who actually use your site totally.
Great so you ignore all the 'better' free AV suites everyone with a slight clue uses and just test the ones that get loaded on as crapware for unsuspecting users. I make a living removing those very suites.Way to miss the point for the people who actually use your site totally.
Exactly my thoughts, where are the tests for Avast, NOD32 ect... Just two anti-virus apps which kick the hell out of the bloated rubbish you've tested. Nowadays with quad-core and six-core cpus on the market impact on performance is negliable as the test results show. The thing that annoys me is all the suites you tested have an appauling impact on peoples systems. They are far to bulky, constantly report false positives resulting on people deleting important system files and an even bigger pain in the arse trying to uninstall them.
Kaspersky Security Suite thorws up overly technical and scary popups like it has tourettes syndrome.
"The file Explorer.EXE has tried to activate itself! Which one of our arbitrary and totally baffling Security Trust Zones do you wish to put it in?"
Please can you do the tests again for AV apps that normal people in the real world actually use such as -
MS Security Essentials
AVAST
NOD32
AVG Free
Avira
The results are likely to remain about the same regardless of which package you use, so testing what they did instead of the free programs that a lot of people use probably does not make much of a difference. What bugs me about security packages is all of their false positives and all of the workarounds you have to use to get normal programs to run without interferance (looking at you, norton), but I guess theres no real way to test that. Anti virus packages may not directly slow down your system, but they may very well make it a pain to install and run new (or old) programs. As far as virus scans go, well, if a virus scan starts while I'm playing even something as simple as d2 I still notice a drop from a constant 60fps down to an unstable 30 or so, and thats on a dual-core machine with dedicated graphics.
My experience of using a particular anti-virus package (AVG 9 free), seems to contradicts these findings. I haven't put it down to one system, either; the same happened on Intel Pentium III's, Pentium IV's with HT and also AMD Athlon XP's right upto Dual-Core AMD Athlon's. There was a very noticeable performance boost from taking it off.
Basically, I find AVG Free 9 a bloated crawler, one that is forever 'tinkering' with the hard drive whilst I'm trying to do other things. Earlier versions of AVG were much faster, and yes AVG free is just that..free, so I'm grateful they at least offer something for nothing to keep your computer safer. So all due credit for that.
I think AVG Free is ultimately a victim of it's own popularity as well as hyped-up expectations. It seems to take up far too many resources for my liking. Avast seems better, but each to their own.
Regardless of these benchmarks, one gets a gut feeling about the impact anti-virus software has on your system and after many, many installations of the same package all having the same affect, you go with that gut feeling. If AVG Free was more compact, less intrusive (eg more like Avast), I'd reconsider using it.
AVG was the AV of choice for many of us years ago but as you mention it has surpassed its initial reason to be. Like a lot of applications (Nero is a prime example) its been padded and bloated out beyond what it was intended for. As a result performance has suffered.
All machines I build now have MS Security Essentials installed. No false positives, no hassles, no pop ups and a low footprint. Try it.
when you read a comment theres a vote tab on the same line, bet loads did what i just did and voted for a spam post, make the forum more clear please ffs.
well I run the free avg on my laptop (single core ) and it comes to a crawl with it on so i have to disable it after its initial checks otherwise the laptop is unusable...is this just because im using the free anti virus one....???.
Please take a pack of 1000+ .exe files and try to copy them somewhere with an anti-virus on. It will take between bloody ages and forever.
In fact, any sensitive extension file that is being worked with is slowed down significantly, specially complex .exe files.
Other then that, A-V software sometimes acts worse then a virus. Try using memory editing tools or various hex-editing or special network tools. The A-Vs will block you by default.
Strikes me some middle ground was missed in the testing. Lab tests say one thing, user experience says another. Although it cannot be tested for, most users dont have a crisp fresh OS install with no apps. They have isntalled plenty of apps and have a disk system running a year or more of fragmentation (because the average user whom is interested in this reports findings wont be defragmenting or running a lab clean PC).
I think the answer to all this fellow users is run a fresh OS isntall with no apps and your AV will be un-noticeable. Install a printer and you've had it.
AVG rules. Has no peer.
As a business developer (visual studio .net) I would have been interested to see how it affects say , compiling a large application.
When I looks at the disc read usage of Macfee (Our corporate AV) it generates as much or more disc reads as anything else that I run, including VB.
Every time you compile a large app you are touching literally thousands of source files, regeneration tens or hundreds of DLL'd PDB files.
You can see the AV hogging CPU and Disc resources whilst compiling.
"a user can confidently install a virus scanner or Internet security suite without being too concerned about performance consequences"
Hmm - who paid for that statement, I wonder?
On older machines (what most people have), Norton and McAfee in particular pour treacle in the works. AVG used to be good, but is now bloatware. I'm no apologist for Microsoft, but MSE is impressive - light, fast and user-friendly. And free.
Kaspersky Internet Security dislike some games. It is not enough to put the folder where the game runs in the exception list, you have to declare EACH. AND. ALL. EXECUTABLE. IN. THE. FOLDER. AS. EXCEPTION. TOO.
When there is a new game, some security suites leave you with a "let it run anyways and don't bother me again" button. Not this one. It just says "I disabled it" in a buttonless box. Pretty dumbed down, way down. It managed to be *noticeable* in a Core i7 920 when this thing trips.
Having used F-Secure and then Nod32 for years, with very few problems, I eventually switched to MS Security Essentials.
Apart from being free, which is always a bonus, I find it works very well with no loss of performance. It is easily configurable to ignore some of your trusted files, can be scheduled to run a full scan whenever you want and as often as you want. It updates regularly as well.
I am really impressed with its functionality and it gives a feeling of confidence in it. High praise for a [b]free[b]full security suite.
Yet it is left out of your tests?
As other people have said, people do not run clean newly installed pc's, so actually this article is pointless!
Of course a security suite will make little difference to performance when it has no files to scan. When it has a boot drive plus a large storage drive or two, filled with music, photos, games, documents, PDF's, downloaded files, emails with attachments, photo enhancing software, an assortment of burning software and maybe even a crack or two etc etc, [b]THEN[b] it will slow a system down! Especially if it decides to scan your drives while your gaming or video file converting!
Regardless of your cpu and memory config, you will notice it!
To me in this modern hardware world, unfortunately this article just states the obvious. I don't doubt that it would be difficult to do a valid test in the circumstances I have described, but a theoretical test gives the same false positives as some of the security programs you tested!
I love the way people are still irrationally biased of some of the more popular software suites that are out there...
this article is about as close to conclusive proof that I have ever seen that antivirus software has virtually no performance impact on a modern PC.
in the face of this, it's idiotic to call them 'bloated crapware' unless you can name an antivirus suite that actively improves system performace.
Personally I use NIS2011 (prev 2010), £20 for a year on 3 pc's and Msft security essentials and have had no problems with performace or viruses.
I think this article proves one thing, the days are long gone when you had to exit your resident AV to get playable frame rates on your games...