I am trying to obtain the highest performance from my Xubuntu system, disabling anything that I don't need.
How can I disable thumbnails on Xubuntu?
Oh well, I figured it out. Open a File Manager window, go to Edit -> Preferences, and set Show Thumbnails to Never.
The way I took care of it is this:
chmod -R -w ~/.thumbnails
I've never had another thumbnail since, no matter the program or preferences.