Interesting. I am running Ubuntu from a CD on a computer with no hard drive. Once everything gets loaded Firefox is very fast or faster then my computers with Windows?
If you want to speed up Firefox in Windows, Linux, etc., give the tweaks a shot @ the following web site.
Link To Speed Up Firefox
While you are at it, shut off prefetch (see the following link).
Link To Shut Off Prefetch.
After applying these tweaks you should see a major difference in speed no matter what operating system you are running!