A free tool SpeedyFox is designed specially to resolve that problem. The method used in SpeedyFox is 100% safe for your profile (e.g. bookmars, passwords, etc)

this program  allows you to optimize Firefox and decrease the startup time, also decreased the time for the history and cookies ….

The program needs no installation so you can easily bring in a pendrive or any other device.

click here to download

To function properly when you run the program make sure that Firefox is closed, otherwise the changes will not be made, reboot, and enjoy your firefox.