Just tried Firefox 7.0. It is faster.
The latest version of Firefox has the following changes:
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
more with Firefox 7.0 releasenotes