Waterfox is a Firefox-based browser especially designed for 64-bit operating systems. Waterfox uses the same profile that Firefox does. If you uninstall Waterfox make sure you don't have the remove personal data box ticked!
Waterfox is basically a 64-Bit version of Firefox. The Firefox source code is taken and compiled to run specifically for 64-Bit Windows computers. To make Waterfox stand out a bit more, it’s compiled with optimizations so that it will run more efficiently and faster than just compiling Firefox as a 64-Bit program.

What's New in This Release:
· Firefox can now migrate your bookmarks, history, and cookies from Google Chrome
· With Sync enabled, add-ons can now be synchronized across your computers
· The CSS text-size-adjust property is now supported
· Redesigned media controls for HTML5 video
· The outerHTML property is now supported on HTML elements
· View source syntax highlighting now uses the HTML5 parser (see bug 482921)
· The Style Editor for CSS editing is now available to web developers
· Web developers can now visualize a web page in 3D using the Page Inspector 3D View
· SPDY protocol support for faster page loads is now testable
· XMLHttpRequest now supports HTML parsing
· Files can now be stored in IndexedDB (see bug 661877)
· Websockets has now been unprefixed
· Fixed where Firefox notifications may not work properly with Growl 1.3 or later (691662)
· Switched from the ACML to AMD LibM
· Compiled with the following flags: -Og -Oi- -Ot -Oy -Ob2 -Gs -GF -Gy -GS- -GA -w