Anyway, here is how to almost completely kill the FireFox disk cache, I thought it's nice to have it cached in here as well:
- Open Firefox. Go to the address bar, type about:config and hit [Enter].
- Type "prefetch" into the search box. You should see an option called "network.prefetch-next" which you can double-click to change to "false."
- Search for "cache.disk" this time. Change "browser.cache.disk.enable" to "false" and change "browser.cache.disk.capacity" to "0."
- Close and re-open Firefox.
- [Update for newer Firefox versions] Firefox stores thumbnails of pages you visit for the new "New Tab" page previews. To get rid of this while you're in about:config, right-click somewhere and go to New -> Boolean, call it browser.pagethumbnails.capturing_disabled and set it to true. Restart Firefox and no more behind-your-back thumbnails.
By the way, there is a jumplist cache"C:Users<user id>AppDataLocalMozillaFirefoxProfiles<profile id>.defaultjumpListCache" which I haven't figured out how to kill yet. I will add it here if I ever find out. I could kill the access to the folder from the "Security" tab but those icons aren't too big to worry about I suppose.