If you put [about:cache?storage=&context=] into the url bar of your browser, both the offline cache will show the file path.

You can make a copy of the profile while Firefox is closed and put it in a new profile. Back up and restore information in Firefox profiles

First off, the cache folders aren't actually in the Firefox program files area, they are in the /local settings/application data/ folder area of the drive where your operating system is installed.

I used to use this pref [probably the last time was like 2007] to move the cache to a different logical disk, away from the Profile folders. http://kb.mozillazine.org/Browser.cache.disk.parent_directory Note - that article does say that preference needs to be created, it was never in about:config until the pref was created by the user.

I have no idea if it still works or not, but I thought i would offer it as something to try out.