There is another tool that I use in both Windows and Linux that does a more thorough job of cleaning
Firefox than Ccleaner.....BleachBit. Along with removing cookies from Dom Storage it also vacuums sqlite. Many claim that
vacuuming Firefox speeds it up.
If you decide to use it, be sure to check the options to vacuum and clean Dom Storage in Firefox.
BleachBit - Clean Disk Space, Maintain Privacy
BleachBit quickly frees disk space and tirelessly guards your privacy. Free cache, delete cookies, clear Internet history, shred temporary files, delete logs, and discard junk you didn't know was there. Designed for Linux and Windows systems, it wipes clean a thousand applications including Firefox, Internet Explorer, Adobe Flash, Google Chrome, Opera, Safari,and more. Beyond simply deleting files, BleachBit includes advanced features such as shredding files to prevent recovery, wiping free disk space to hide traces of files deleted by other applications, and vacuuming Firefox to make it faster. Better than free, BleachBit is open source.
“Every atom in your body came from a star that exploded and the atoms in your left hand probably came from a different star than your right hand. It really is the most poetic thing I know about physics...you are all stardust.”― Lawrence M. Krauss
A 1792 U.S. penny, designed in part by Thomas Jefferson and George Washington, reads “Liberty Parent of Science & Industry.”