One thing that might help, too, is something I discovered on my (SuSE) system.
When I loaded FF it, too, ran slow compared to Win2K on my syteem. (I have a dual-boot configuration with seperate hard drives.)
I eneded up disabling IPv6 and firefox took off like a mouse of of a cat convention.
It now runs faster loading pages (using a stopwatch) than it doesn on my Win2K side. In fact, using Suse 9.2 (as compared to Mandrake or Suse 9.1) it is overall faster doing things than Win2K. (Let's not even get into this POS WinXP that I'm forced to use at work.)
You might also run a comparible speed test. For example, I often test my page loading speed and NIC config. Here's the stanford linux tool: http://www.stanford.edu/~preese/netspeed/
and the web-based java application: http://netspeed.stanford.edu/
I know Stanford is a private school and may not be as reliable as state schools, such as UCLA, but it is a pretty good test.
Anyway, run this test in Windows then in Linux see if there's any difference. If there is, you may have some NIC configuration to perform.