Best Free AV for a low RAM computer?

[Nagisan]

In short, what is the best free anti-virus you can use on a computer which only has 512MB of ram?

I generally prefer MSE as a free AV, but I have found it tends to run like crap on any computer with 512MB of ram and makes the whole computer run dirt slow, even on an XP install. So, I am looking for an AV that will run well on 512MB of ram without bogging down the system.

[Nagisan]

Any suggestions? Pretty much done setting up this computer, just waiting to see which AV I should put on it given its low ram.

[Hani]

Avast or MSE.

[opensuse]

Antivir

[Roger H. Veteran]

My vote goes for MSE.

[still1]

MSE for sure. lite and free.

[SfIsHeR1701]

The OP said in his post that MSE slowed his computer down. I think a big solution will not be to change your anti-virus, but increase the ram... ram is dirt cheap, even just doubling it to 1gb will make a world of difference (assuming you are running XP)

[skinnypete]

MSE for me as well. I recently worked on a really old Dell (PIII vintage) with 512MB. That machine is working pretty for being so old.

[Roger H. Veteran]

I've never used it but i've also heard good things about Panda Cloud AV. Might be worth checking out.

[KyleGM]

MSE, probably the best AV I've used, barely even notice it's there :)

[Astra.Xtreme]

Any antivirus is going to run pretty badly on 512mb of ram.

[Nagisan]

The OP said in his post that MSE slowed his computer down. I think a big solution will not be to change your anti-virus, but increase the ram... ram is dirt cheap, even just doubling it to 1gb will make a world of difference (assuming you are running XP)

Sadly it is not my computer, so simply increasing the ram is not an option. I had MSE running on it before and it just seemed really slow compared to before I installed it. Trust me, if I could, I would increase the ram. To give you an idea of how old the computer is, it has an AMD Athlon XP-M 2800+ processor (1.6Ghz) , with only 512MB of ram, and it came with a CD-ROM drive. It now has a DVD drive in it as well, but its so old it actually came stock with a CD drive only.

If MSE is one of the lightest AVs then so be it, I will simply stick with it on this machine, was just hoping there was something out there that was a bit lighter.

[Bhav]

Comodo

[+Warwagon MVC]

I'd Vote Avast. Version 5 is really nice.

[MagicAndre1981]

Avira AntiVir. MSE slows down older PCs.

[+Xinok Subscriber²]

From personal experience, I can say that Avira Antivir is the fastest antivirus, followed by Avast and last MSE.

As for memory usage, I decided to do an actual test in a virtual machine. Windows XP 32-bit, 384mb RAM. I installed the antivirus and rebooted afterwards. The screenshots were taken after the OS was fully booted.

MSE comes in first with 240,460 KB available.

Avast comes in second with 219,568 KB.

Avira Antivir had the least RAM available, at 181,628 KB.

Avast

Avira Antivir

Microsoft Security Essentials

[TDT]

MSE, all the way.

[Tarzan]

Ram usage is of little importance even with only 512mb though not entirely sure about MSE! What slow down computer is cpu usage and hd activity while AV is doing real time protection. If an X AV take 1 hour longer than Y to do a full scan it can still be faster and easier on computer. The big news in Avast 5 is that after a full scan only new or modified files will be scanned = minimal overhead. Also possible to deactivate modules not really doing much good. File System Shield is enough but probably useful to add network shield since it blocks malware domains. The also new behavoir blocker should of course also be used but I have no idea how effective/relevant to real usage it is.

You should test with task manager, process explorer/monitor after a full scan and over a period of time doing different tasks.

Xinok: check system cache relationship to avail memory, but unless real numbers monitored under real conditions for relevant processes are crazy it does not matter that much. I know MSE can use 80-120+mb on 64bit Windows so not 100% sure about that one. Should use less on a 512mb XP computer I would guess. But a static 1kb is still no good if it slows down computer. If Avasts http scanner slow down browsing, cause cpu spikes or whatever it is also no good.

[TokiToki]

Sadly it is not my computer, so simply increasing the ram is not an option. I had MSE running on it before and it just seemed really slow compared to before I installed it. Trust me, if I could, I would increase the ram. To give you an idea of how old the computer is, it has an AMD Athlon XP-M 2800+ processor (1.6Ghz) , with only 512MB of ram, and it came with a CD-ROM drive. It now has a DVD drive in it as well, but its so old it actually came stock with a CD drive only.

If MSE is one of the lightest AVs then so be it, I will simply stick with it on this machine, was just hoping there was something out there that was a bit lighter.

I'm a few days late, but I can say with experience that MSE is dog slow on an Athlon XP computer (I have an old XP 2500+ computer). MSE consumes a lot of CPU resources for long periods of time on that machine. I personally use Avira Antivir on that machine and it much lighter than MSE.