You could always grab the firefox source code and compile it yourself.
Tweaking Firefox/Iceweasel tends to speed up the internet part, and using prelink helps it load much faster.
My Iceweasel user.js tweaks:
http://www.geocities.com/reverendsky....0settings.txt
How to load programs faster (prelink)?
Install package: prelink
(sudo apt-get install prelink)
sudo cp /etc/default/prelink /etc/default/prelink.`date +%y%m%d-%H%M%S`
Edit "/etc/default/prelink" as root, and find this line:
PRELINKING=unknown
Change it to:
PRELINKING=yes
Exit from kwrite, saving the file.
sudo prelink -avmR
sudo /etc/cron.daily/prelink