According to PCMag.com, Mozilla claims the MemShrink project reduces memory use by 20 to 50 percent.
the release notes is available
The latest version of Firefox has the following changes:
Please see the complete list of changes in this version. Web and extension developers should also view the curated list of platform changes. You may also be interested in the list of changes in the previous version.
- Drastically improved memory handling for certain use cases
- Added a new rendering backend to speed up Canvas operations on Windows systems
- Bookmark and password changes now sync almost instantly when using Firefox Sync
- The 'http://' URL prefix is now hidden by default
- Added support for text-overflow: ellipsis
- Added support for the Web Timing specification
- Enhanced support for MathML
- The WebSocket protocol has been updated from version 7 to version 8
- Added an opt-in system for users to send performance data back to Mozilla to improve future versions of Firefox
- Fixed several stability issues
- Fixed several security issues
Firefox 7.0 is available in over 70 languages, and is available here.