From there web site here is the Main Features of this development:
See http://www.palemoon.org/ for more detailed information.Optimized for modern processors
Firefox sourced: As safe as the browser that has seen many years of development.
Uses slightly less memory because of disabled redundant and optional code
Smooth and speedy page drawing and script processing
Increased stability: experience fewer browser crashes.
Support for SVG and Canvas, and downloadable fonts including WOFF
Extensive support for HTML5, CSS3 and WebGL
Support for Firefox extensions (add-ons) and themes
OOPP (Out-of-process plugin execution) to prevent browser crashes
More customization and configuration options than Firefox
Able to use existing Firefox profiles with the migration tool
*cheers Mabs!