When i started out on Linux more specifically openSUSE 11.0/Gnome i had trouble browsing the internet using firefox , seamonkey.The browser would work well for the first minute then it would be non responsive or very slow in loading the pages.The same problem would not occur on opera.
The issue seems to have been with my network connection couldn't support IPV6 protocols.This issue should afflict other gecko based browsers like flock
The issue was solved using the following solution:-
In firefox address bar type in "about:config" and press return/enter
Then accept the warning page
Look for .. network.dns.disableIPv6 and set it to "true".
This will fix the problem instantly