Firefox is the browser of the most favored, because Firefox is one of the fastest browser.
Firefox claimed to be the fastest and less useful in memory usage.
If you are a firefox user browser, here are some tips to speed up again your Firefox browser.
If we often do browsing, Firefox was saving our history into the database and the database can cause slow startup process firefox.
To overcome this you can use the add-ons called Vacuum.
Add-ons Vacuum serves to “tidy up” the database files so they can optimize firefox firefox speed when performing loading.
Download and install these add-ons and you can feel the changes.

https://addons.mozilla.org/en-US/firefox/addon/13878