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)