Try a test to see if it's a bad setting in your config/chrome directory. In the command listed below, I'm not certain that a .firefox directory even exists. I doubt that it does - it's probably all just contained within .mozilla but I put the commands there just in case. Everything below is done as your user - not root.
with all browsers closed, change the name of your mozilla (and firefox) config directory:
mv ~/.mozilla ~/.mozilla_backup
mv ~/.firefox ~/.firefox_backup
Then simply start a browser and notice if it behaves any better. If it does, then likely the problem is just something in the config files of mozilla/firefox. Also, if it's working better then maybe just importing your settings into this new configuration would be a good option.
You can put your old configuration by first closing all browsers and then issuing these commands:
mv ~/.mozilla ~/.mozilla_new
mv ~/.firefox ~/.firefox_new
mv ~/.mozilla_backup ~/.mozilla
mv ~/.firefox_backup ~/.firefox