Level 3
I know it depends... But I just need th LOWEST POSSIBLE antivirus impact that could be achieved.

So is it really the Panda Free Antivirus even better than Windows built-in Defender?

Let me know, what you guys think :)
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Level 15
Windows Defender peaks the CPU usage only when opening a folder with lots of executables. So unless you're an AV tester, WD should be fairly light for you, plus the advantage of being absolutely free and not nagging you.
Some say ESET is the lightest, others talk about Panda, I recommend you to test for yourself and see what works best in your machine.


Level 12
@roger_m I agree with you, its just part of windows and on some versions or editions of windows, it is quite difficult to turn it off completely. its embedded in so many parts of windows, smart screen, IE, etc, on home or pro versions of windows, even when i turn it off, it still runs in background, updates itself and definitions and request internet access. hence my guess =D

I have used Windows Defender exculsively for about 1 month testing windows defender advance threat protection and it has come a long way and I didn't notice any hiccups on resources.


Level 1
From my experience Webroot is definitely the lightest. ESET and Norton are also very light on the system. Bitdefender, Kaspersky and Trend Micro tend to be on the heavy side. I've also noticed that Windows Defender tends to be on the heavy side, as most of time my PC will end up running faster with most other AV. On the other hand if you have an i9 with an SSD, you probably won't notice much difference ;)

In my opinion RAM usage is not an important factor to see how light a security software is, except on older hardware. You might have an AV that takes 500 mb but won't slow down the system, and vice versa. There are other things to take into consideration, such as how fast files are scanned upon startup, how efficiently the web filter works, etc...

But again that's just my personal opinion.


Level 31
On the basis of the topic I would say Panda or ESET.

Swinging the topic around, but staying on subject, having the lightest AV may not generally be the best or the most suitable for your computer.

It's like dieting your computer, without the need for a diet sometimes, especially if one's computer has an SSD installed.



Level 16
Content Creator
There are some great light options mentioned, but these "performance tests" which seem to be all the new rage on YouTube, have to be taken with a grain of salt. They seem to be the new right click scan folder with real-time off and run missed files with real-time on tests, but focusing on performance rather than protection.

I agree with what has been said above, you have to try the programs for yourself and see what you think. There are way too many variables to give a blanket statement on which one is better performance wise, different software/hardware configurations and everyone uses their system differently. For example IMHO WD is barely noticeable in most day to day operations, but if you are one that installs/uninstalls a lot of programs and transfers a lot of files, it suddenly becomes more noticeable due to the way it scans, but if you aren't doing those things frequently you don't notice it.

One thing to note with these tests, is that they are being done in a VM. While I understand it's an easy way to test a lot of configurations quickly, it's a very poor way to gauge performance, as the VM will never truly be as fast as running it directly on the host IMHO. The VM will introduce it's own issues when it comes to performance. Furthermore, with running a bunch of "bench-marking" tests, you have to remember that you can measure things to such fine detail that to us humans a 100-200 point difference (heck even maybe a little more) will not be noticeable at all.

At the end of the day, tests are fun, shouldn't be taken a fact and one needs to try each program for themselves in order to find out if it meets your needs.
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Level 3
THANK YOU, GUYS for all your imputs :)! I really love this forum.

Well, it really seems like it depends on a lot of factors. I have a friend, he's a total noob and his PC is terrible. I currently left Windows Defender on, but he was able to install some kind of adware on his system ("you have been infected with a virus and you need to download this app to remove it"). So it's really not an easy option for me... :/

As @TairikuOkami noted - cloud-based AV's should be the lightest, so I'm thinking about Comodo Cloud Antivirus (while I'm still avare that no solution is fool-proof, but I just want to have at least some basic level of protection, regardless of good is it in protection, if you know what I mean).


Level 3
Looking at more traditional solutions I find either ESET ot Norton makes very little difference on any of my PC's either in moving large files/imaging, stability etc - Norton going cheap cheap on Amazon elsewhere on site.
I'll try to find his exact config, but I really doubt that his PC would be able to handle either ESET, or Norton... :(


Level 27
Content Creator
I kind of think forticlient is the one, that has low impact on performance

Taken from pcinsider

System Impact & Resource Usage
Hard Disk Used: No Offline installer of FortiClient is available. You have to download the Online Installer to download and install the antivirus. The FortiClient Installer downloads the FortiClient Virus Scanner and the FortiClient Setup file. The scanner is of about 10 MB and the setup is of about 30 MB in size. After installation and an update, the FortiClient Free Antivirus uses around 600 MB of the disk space.
CPU and RAM Usage When Idle: FortiClient runs many processes in the background. However, they don’t impact the system performance at all. It uses only about 50 MB of RAM between all of those processes. The CPU usage is stable at 0%.

CPU and RAM Usage When Scanning: There is not much impact on the system even when FortiClient is scanning it. It uses only about 60 MB of RAM while performing a full system scan. During Scanning, two processes of FortiClient use the CPU power – av_taskand FortiClient Console. The CPU usage of the av_task process fluctuates between 5 to 15%, and is stable at around 10%, and the CPU usage of the FortiClient Console process fluctuates between 8 to 12%, and is stable at around 10%. So, a total of about 20% of the CPU power is used continuously while performing a full system scan.

Source: https://www.thepcinsider.com/forticlient-free-antivirus-review-windows/

My personal opinion: I think the pcinsider review was pretty accurate, and forticlient still stays underrated antivirus. But as we have heard theyre probably having updates anytime soon this year with the possible machine learning, wich could make it even more impressive/ less impact

I kind of think that the parental filter/ web filter of forticlient is best of the available ones and when having safe internet habits+ adblocker you probably never will get infected its kind of impossible.

Just combine smartscreen ( respect the prompts) and something like syshardener with it and you have zero impact protection and everything pretty much covered +
Ps. forticlient also has vulnerability scan wich is kind of useful, if youre not using the windows 10 (i guess)