The final build for Firefox 7.0 has been launched (for Linux, Windows, and Mac). This is a stable release that fixes a previous issue that made Mozilla Firefox 
run slow. The memory leak problem has disturbed Mozilla for years, and it has finally been resolved. Memory inconsistencies were addressed using MemShrink, an initiative that was started this June.
With no memory leaks and fewer OOMS, there will be less aborts and crashes. The new browser uses far less memory than the previous versions (about 20% to 50%).
Other changes will be noticed in the look and feel of the browser, including the changes in its ‘awesome bar’. The new and latest Mozilla 7.0 is ready for download.
And if you are looking for some adventure, you can try downloading Firefox v9 nightly, or Firefox Aurora v8. But these are only for developers and experienced users.
Installation
1- Download :
For 32 bit use this command to download firefox7.0
wget ftp://ftp.mozilla.org/pub/mozilla.org/firefox/releases/7.0/linux-i686/en-US/firefox-7.0.tar.bz2
For 64 bit:
wget ftp://ftp.mozilla.org/pub/mozilla.org/firefox/releases/7.0/linux-x86_64/en-US/firefox-7.0.tar.bz2
2- Now extract and move the folder to /opt
tar xvjf firefox-7.0.tar.bz2
sudo cp -r firefox/ /opt/firefox
sudo rm firefox-7.0.tar.bz2
sudo rm -r firefox/
3- Make a Symbolic Link
“Backup” the old Firefox launcher:
sudo mv /usr/bin/firefox /usr/bin/firefox-old
Create a symbolic link pointing to the new Firefox version:
sudo ln -s /opt/firefox/firefox6 /usr/bin/firefox
