So to try it out, I disabled the remote desktop sharing using the 'vino-preferences'. This fixed my CPU utilization.

To give this a try, just type 'vino-preferences' on your shell:
1) then just uncheck the 'Allow Other users to view your desktop' checkbox under 'Sharing'
2) Press 'Close'.
Hopefully this will be helpfull to someone.
If this does not help, you may also try
1) Make sure you have FireFox latest updates
2) Try disabling(i.e Selecting 'None') Visual Effects from System->Preferences->Appearance->Visual Effects.
3) Disabling CPU Frequency Manager from System->Administration->Services