CCleaner is not an Anti-Virus. It does not run in the background (at least the free version) and will not slow your PC. It helps users locate and remove temporary/cache files buried in the OS to free up disk space. It is very useful - even for pros. Defender will not do this.
CCleaner does sell a bit of FUD though - "your computer is slow, use us so it goes faster". I don't think "crap" is causing significant slowdowns anymore, maybe frees up some disk space but nothing that the OS can't do itself either.
CCleaner is also essential for cleaning up poorly uninstalled apps leaving registry keys lingering around. It's also great for when you need to fully reset and reinstall a misbehaving app, such as Symantec Endpoint Protection, which fails to clean up several critical registry keys that it checks during installation, and then refuses to re-install if they exist. Sure, you could hunt them down and write a script for Symantec, but CCleaner does it for all apps. I've fixed so many terrible apps and installs using CCleaner, it's an absolute necessity.
That and RevoUinstaller. You run RevoUinstaller then CCleaner, and maybe a reboot in between, and you've really removed an app. (The paid version of Revo is even cooler, as it will let you log the files generated during an install, and then on uninstall, it'll make sure to remove all the files and directories you had previously logged.)
I have always assumed the vast majority of software meeting this description is malware. I don't know if I should feel silly or if it's a sensible assumption for end users to make.
Categorically disregarding the use of automated maintainence tools under the guise of "lazy vs real techies" seems short sited, arrogant, and regressive.
It may be more expensive but hand-crafted, artisanal system administration is well worth it. The difference between it and cheap, factory produced system administration is night and day. Also, it's Local and Made In The USA so you are helping people around you in the greatest nation on earth rather than poor people in another country.
The latest Win 10 has a new setting that vaguely indicates it will look for and delete temporary files automatically. On my machine it was not turned on by default.
No idea how much it gets vs. leaves behind and since turning on it hasn't thrown up any obvious notifications lauding itself.
This is on a secondary machine. My primary machine isn't Windows.
I use CCleaner for maybe even 10 years, a great tool.
But Windows 10 (a few older versions as well, but somewhat hidden) has something similar called "Disk Cleanup" (Win key > enter "Disk Cleanup" > "Clean up system files" > Check all marks). "Disk Cleanup" removes stuff that CCleaner doesn't, so I use them together.
You can even remove system restore and shadow copies (Win key > enter "Disk Cleanup" > "Clean up system files" > "More Options" tab > "System Restore and Shadow Copies" > "Clean up" button).
