By default Firefox puts its cache in your home partition.You can speed up Firefox and reduce disk writes by moving this cache into RAM if you have 1GB RAM or more.
1.Edit /etc/fstab,open terminal from Applications->Accessories menu and type:
sudo gedit /etc/fstab
Add following into this file and close it.
tmpfs /tmp tmpfs noexec,defaults,noatime 0 0
tmpfs /var/tmp tmpfs noexec,defaults,noatime 0 0
sudo gedit /etc/sysctl.conf
add this line and save it:
about:config in firefox address bar and click
I'll be careful,I promise!.Right click on blank area and create a new string value called browser.cache.disk.parent_directory,set its value to /tmp
Now,reboot your system and experience the performance.
Original text:HOWTO : Ubuntu 9.04 Desktop on Solid State Disk (SSD)