[DarkMuse]

None of those will do anything to help, aside from reducing startup programs. The best way to keep your PC as fast as possible is to eliminate any background programs you don't need, defrag your disk regularly, and run antivirus software to keep your system malware free. It's also helpful to regularly dust your machine and keep it in a cool environment.

You don't need antivirus software to keep your system malware free if you're not downloading child porn off the deep web. Furthermore, antivirus is a system process and it will inherently slow down your system.

I've definitely seen this with certain AV but not all (I'm looking at you McAffe, Malwarebytes, AVG). Webroot and BitDefender have some of the best detection and removal scores within the industry and take up very little memory with an active scan module as well as browser monitoring. I mainly use it when using something that might potentially dangerous as I'm not too trusting of sandboxes (not all that trusting of AV either but more than sandboxes).