Memory Usage Test to See Which is the Lightest Antivirus Software

12. Kaspersky Anti-Virus

kaspersky memory usage

Number of Processes: 2
Processes Monitored: avp.exe, avp.exe

Idle Working Set (KB): 65,625
Idle Private Working Set (KB): 52,218

Scan Working Set (KB): 103,377
Scan Private Working Set (KB): 92,105

11. Bitdefender Antivirus Plus 2013

Bitdefender antivirus memory usage

Number of Processes: 5
Processes Monitored: bdagent.exe, downloader.exe, updatesrv.exe, vsserv.exe, odscanui.exe

Idle Working Set (KB): 81,360
Idle Private Working Set (KB): 47,658

Scan Working Set (KB): 150,478
Scan Private Working Set (KB): 62,877

10. Microsoft Security Essentials

microsoft security essentials memory usage

Number of Processes: 3
Processes Monitored: MsMpEng.exe, msseces.exe, NisSrv.exe

Idle Working Set (KB): 70,484
Idle Private Working Set (KB): 51,750

Scan Working Set (KB): 79,103
Scan Private Working Set (KB): 57,787

9. F-Secure Anti-Virus 12.77 build 100

F-secure antivirus memory usage

Number of Processes: 7
Processes Monitored: fsgk32.exe, fshoster32.exe, FSM32.exe, FSMA32.exe, fsorsp.exe, fssm32.exe, fsblsrv.exe

Idle Working Set (KB): 62,042
Idle Private Working Set (KB): 40,246

Scan Working Set (KB): 92,386
Scan Private Working Set (KB): 66,819

8. AVG AntiVirus Free 2013.0.3272

avg memory usage

Number of Processes: 7
Processes Monitored: avgcsrvx.exe, avgemcx.exe, avgidsagent.exe, avgnsx.exe, avgrsx.exe, avgui.exe, avgwdsvc.exe

Idle Working Set (KB): 194,888
Idle Private Working Set (KB): 34,398

Scan Working Set (KB): 199,628
Scan Private Working Set (KB): 63,403

7. UnThreat AntiVirus Free 2013

unthreat antivirus memory usage

Number of Processes: 2
Processes Monitored: utsvc.exe, UnThreat.exe

Idle Working Set (KB): 13,615
Idle Private Working Set (KB): 8,953

Scan Working Set (KB): 87,027
Scan Private Working Set (KB): 73,778

6. Immunet Free

Immunet memory usage

Number of Processes: 2
Processes Monitored: agent.exe, iptray.exe

Idle Working Set (KB): 40,413
Idle Private Working Set (KB): 29,304

Scan Working Set (KB): 63,475
Scan Private Working Set (KB): 45,510

5. Norton AntiVirus

Norton Antivirus memory usage

Number of Processes: 4
Processes Monitored: ccsvchst.exe, ccsvchst.exe, ccsvchst.exe, ccsvchst.exe

Idle Working Set (KB): 59,304
Idle Private Working Set (KB): 19,362

Scan Working Set (KB): 111,094
Scan Private Working Set (KB): 52,576

4. Panda Cloud Antivirus Free 2.1.1

cloud antivirus memory usage

Number of Processes: 4
Processes Monitored: PSUNMain.exe, PSUAService.exe, PSUAMain.exe, PSANHost.exe

Idle Working Set (KB): 31,714
Idle Private Working Set (KB): 20,340

Scan Working Set (KB): 76,498
Scan Private Working Set (KB): 41,172

3. Comodo Antivirus Free 6.1.275152.2801

comodo antivirus memory usage

Number of Processes: 4
Processes Monitored: cavwp.exe, cis.exe, CisTray.exe, cmdagent.exe

Idle Working Set (KB): 39,664
Idle Private Working Set (KB): 14,954

Scan Working Set (KB): 105,317
Scan Private Working Set (KB): 34,453

2. Webroot SecureAnywhere AntiVirus 2013

webroot secureanywhere memory usage

Number of Processes: 2
Processes Monitored: WRSA.exe, WRSA.exe

Idle Working Set (KB): 3,823
Idle Private Working Set (KB): 2,726

Scan Working Set (KB): 9,949
Scan Private Working Set (KB): 7,673

1. Avast! Free Antivirus 8.0.1483

Avast memory usage

Number of Processes: 2
Processes Monitored: AvastSvc.exe, AvastUI.exe

Idle Working Set (KB): 9,706
Idle Private Working Set (KB): 4,290

Scan Working Set (KB): Resets every 10 seconds
Scan Private Working Set (KB): Resets every 10 seconds

Results and Summary

The result tables are simply split into two, one for the idle memory usage and one for the usage during a virus scan, both in alphabetical order. The colors are self explanatory with green the lightest antivirus and yellow second best. At the other end, red is the heaviest and orange the next most memory hungry.

Average Memory Scores While Idle

Antivirus average memory usage while idle

Average Memory Scores During a Scan

Average memory usage during scan


  • It was quite a surprise to see a couple of antivirus packages actually using an average of nearly 200MB while sitting idle. ZoneAlarm was also very high in both scores during scanning while the Sophos Working Set score more than doubled. Do note that ZoneAlarm does include a firewall though, and doesn’t have a version without it.
  • On the positive side, Webroot SecureAnywhere proves that cloud antivirus packages can be extremely efficient in memory usage, and it was very good in both idle and scanning scores. You’ll also note that both Working Set and WS Private were very close together so it’s also not consuming shared resources from other programs.
  • Avast is the most popular free antivirus around today, and its memory usage is quite impressive. During scanning Avast kept flushing its memory every 10 seconds which kept usage at a very low level, and it should never grow above a small number of Megabytes. Idle resource usage was also very impressive. For efficient memory usage, Avast is the no.1 free antivirus by far.
  • Some small surprises were Comodo, Bitdefender Free and Avira for different reasons. While Comodo seems to have improved its memory efficiency in recent times, Avira appears to have gone in the opposite direction. What used to be possibly the lightest antivirus package you could get for free, is now quite heavy on memory usage, especially during a scan. Although Bitdefender’s memory did fluctuate a lot, on average it still consumes a lot of memory for a program with virtually no features or options.

Final Note: While these results obviously test the antivirus memory usage, they don’t take into account the features present in each application and its detection rates. Therefore you shouldn’t automatically assume lighter is better because a more memory efficient program might not have the amount of features of an antivirus using a few more Megabytes. If your current package is hungry for memory, this does give you a good idea of what the lightest antivirus packages are that you might like to look at a bit closer.

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