Im not sure what happens to the files. They are user prefs files for saving your personal preferences of the defaults...mine is set to load up a blank scene with an enviroshere and my own light set. When you throw out those files, Poser just makes new default files and places them in their proper folders. All your settings go away bt you can save new ones so it's no big deal. The end result inmy case is that the library becomes fast again. give it three months and it will be back to the same old slow library.

W10, Ryzen 5 1600x, 16Gb,RTX2060Super+GTX980, PP11, 11.3.740