If you want to find a picture you saw yesterday, and now the picture has been removed from the web site that you saw it on for copyright reasons, *and* you haven’t exited Firefox in many weeks, *and* you have had a web page open on one page that is constantly showing you different parts of the world in Google Maps in hybrid mode, DO NOT try to find the picture by going to your .mozilla/firefox/*/Cache directory and typing “kuickshow *”.
After my screen filled with several hundred images, mostly Google Map tiles, it started getting really slow. My CPU was pegged, I was swapping heavily, and still images were appearing. The mouse was moving, but nothing was responding to clicks or keyboard presses. I went to another machine, ssh’ed in and did a “killall kuickshow”, but the load average was still over 8. I waited a while for it to drop down to under 1.0, but my display was still unresponsive. Eventually I gave up waiting for it to recover and rebooted.
Of course, my Cache directory is now nearly empty and I’ll never find that picture again.