Suppose Firefox is a very fast browser. However, with the lapse of time it starts working much slowly. It is caused by fragmentation of profile databases.

SpeedyFox a free tools to save you from slow speed. Simply download it from here  and run SpeedFox. Once the optimisation work is done, re-open Firefox and feel the difference.

You won't lose any data, password, history, cache with this little tool kit. I would highly recommend you to use this software if you are Firefox user as mine.