Disable Pango for a faster Firefox
Please note: This fix affects the default, packaged installation of Firefox on Ubuntu installations. If you’ve upgraded your Firefox install manually, you do not have Pango installed and ths fix will NOT work.
Pango is a font smoothing library which decreases Firefox speed by up to 45%.
The Firefox version which comes in Ubuntu has Pango enabled by default. To disable Pango open your Home folder (Places->Home Folder) and press ctrl+H and edit your .bashrc or .bash_profile file. Open the file and add this line:
Now save and close the file and re-source your .bashrc or .bash_profile file. Open a Terminal (Applications-Accessories->Terminal) and type:
Now restart Firefox and enjoy a faster Firefox 🙂
Source: Web Upd8