This is really to general of a video. On modern multicore cpu's you won't really notice it. Windows Defender/Antimalware service definitley can have a performance impact. For instance. I have an athlon 760K. I use it to play Modern Warfare. At first the game ran terribly. And I know it's below the minimum requirements to run the game, but I could run it. I just felt like if I could free up some system resources the game might run better. So off I went down a deep Windows rabbit hole. I went through every service that was installed on a clean image. Researched them up and down and disabled everything that is nonessential for windows to boot. Yes. I have no Windows updates, no microsoft store, no windows defender. No powershell. I literally stripped windows down to a bare bones platform. I now have only 68 processes running after boot. Let me tell you Windows is a different animal like this. On a stock clean windows install after boot if my computer was idle my cpu fan would stop running. As soon as I touched the mouse it would go right up to full speed. After I stripped everything even with numerous chrome tabs open my cpu fan would barely kick on every couple of minutes. Disabling the antimalware service knocked my cpu usage down 8-10% at idle. And by disabling it was done through the registry in safe mode, changing permissions, and I was finally able to remove the files and remove the task scheduler items. It was a pain to get rid of it but it can be done. Now I know, i know you're thinking "what kind of idiot runs no antivirus/antimalware software?" Well I can tell you I never have, never will, and I do a lot of neferious things on the internet. Shady programs, shady websites, and such. I've never met an malware I couldn't beat. I actually enjoy trying to clean them. You learn alot. There was only one that I really had a hard time with. I believe it was a cryptominer. I found it because one day I went to play Modern Warfare and when I joined a lobby, which put's a decent load on your cpu, my game crashed. I noticed in task manager my cpu utilization was hovering at 1-2% at idle. This was weird because normally I would sit right at 0%. I checked the running procceses and nothing looked out of the ordinary. I couldn't see what was using the cpu though. I checked event viewer and I noticed there was a couple of events that called powershell to run silently. I checked the files that they were calling and they were normally files that aren't modified. It would also modify multiple random files. It wouldn't use the same file everytime. I checked my firewall on my cable modem and I had 2500 denied attempts in one day all from different ip addresses. Comcast actually sent me a text asking me if I knew these ips and wanted to allow them. I ended up having to reinstall windows to get rid of this one. It was the only malware I've ever had trouble with. Most I can disable and remove. Not this one.