Here is a list with the most significant changes of the 18 release. For a complete list of changes check the release notes.
- Support for Retina Display on OS X 10.7 and up
- Preliminary support for WebRTC
- New HTML scaling algorithm that provides a better image quality experience
- Performance improvements around tab switching
- Support for new DOM property window.devicePixelRatio
- Improvement in startup time through smart handling of signed extension certificates
- Support for W3C touch events implemented, taking the place of MozTouch events
- Disable insecure content loading on HTTPS pages – (62178)
- Improved responsiveness for users on proxies – (769764)
Although things look very much improved for this version in the performance front, you should consider what your daily tasks are and how much you would benefit from upgrading. A discouraging reason for many people out there could be the slow scrolling in the main Gmail tab that is a part of the small but non-disregardable Known Issues list.
If you are willing to install the 18th version of Firefox browser you can either download the Linux package that contains the binary that you can use however you want (example: create a shortcut on your applications overview), or use the following Ubuntu ppa by typing these commands on a terminal:
sudo apt-add-repository ppa:mozillateam/firefox-next sudo apt-get update sudo apt-get install firefox