Psp 9 introduced a Shell Extension Thumbnail handler. I was under the impression it was part of x onwards. This Will make PSP image Thumbs display in explorer windows One fo PSD is also available from MS Power toys and a Nef Cr2 also. for thumbnails of other Raw formats ARC SOFT have a free download.
Note thes are only for sowing the thumbs not opening the image.

Once PSP has cataloged the thumbs It will be relativly idel and the thrashing may have been coused by a corupt data base. You can allow or disallow Psp from cataloguing after you have close PSP in preferences. So making the database writeable and letting it run should get it over and done with providing you not letting it catalogue Multi page PDF files and a HDD full of movies