Slow browsing
I have a fast internet connection on fibre 100Mbit up and down. When testing with tptest that tests speed w-out browser I get around 95Mbit up and down, ping 3ms. But with firefox I have downloadspeed only around 10Mbit and can send files with 85Mbit speed. (With IE it´s download 61Mbit and sending 35Mbit) Puzzling! I use a quite slow netbook, the first EeePC 700 w 2G RAM, XP and Firefox 3.6. I have just reinstalled windows and formated C to clean out computer but did not change anything with firefox. Have disabled puligns-addons and gone through all virus and malware scans possible. Older version 2 something was faster about 25Mbit download but still that is far from available speed.
Opaite Mbohovái (1)
Create a new profile as a test to check if your current profile is causing the problems
See Basic Troubleshooting: Make a new profile
There may be extensions and plugins installed by default in a new profile, so check that in "Tools > Add-ons > Extensions & Plugins"
If that new profile works then you can transfer some files from the old profile to that new profile (be careful not to copy corrupted files)
See http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox