"/usr/lib/kscreenlocker_greet" takes lots of CPU and make fan noise

Welcome to the Manjaro community @Jacob123

I don’t have that option on my Plasma system. My guess is that you are using Plasma on X11, rather than Wayland. You can check your session type by running the following command:

echo $XDG_SESSION_TYPE

If it reveals you are using X11, then you should try switching to Wayland:

You can change your Plasma session from X11 to Wayland by selecting the session type at the login screen (Wayland is the default for Plasma).

If you have set up autologin to skip the password screen, you can change to a Wayland session by opening System Settings → Colors & Themes → Login Screen (SDDM) → Behavior.

If that doesn’t fix the issue, then further investigation may be required, for which some system information would be very useful:

inxi -zv8

Further reading:

As a new or infrequent forum user, please take some time to familiarise yourself with Forum requirements, and the many ways to use the forum to your benefit:


Update Announcements

The Update Announcements contain important information and a Known Issues and Solutions section that should generally be checked before posting a request for support.

System Information

Output of this command (formatted according to forum requirements) may be useful for those wishing to help:

inxi --filter --verbosity=8

or the short form:

inxi -zv8

Be prepared to provide more information and outputs from other commands whenever asked. It’s equally important to provide as much actionable information as possible in your first post, rather than simply indicating there is a problem.

Required reading
Resources

Regards.