I would like a program which would do what AMP Font Viewer does, which is to temporarily install few (or a bunch) fonts from chosen folder, so they could be used by applications (eg. for typesetting) and then again remove them, so they don't slow down the OS and stuff (dunno, how this actually works on Linux, but Windows are slowed on start when they have too many fonts installed). Is there a way (a rather simple way preferably) to do this?
SnapOverflow
I had the same problem. After years of annoying copying fonts by hand, I finally gave up and wrote my own program for this purpose. I'll be glad if it will be useful for you and other people:
https://danpla.github.io/fontlink
You can install fonts locally in
~/.fonts. You'll need to create this folder, and you can drop in fonts into that folder. Depending on the program, you may need to restart your computer.