The Mozilla foundation is de-prioritising the development work on 64bit version of Firefox for Windows. This is a good article which points out why not, while also explaining the benefits of 64bit browsers. It does make me think however – that browsers these days are fundamentally broken.

Source: [Ars Technica.  64-bit Firefox for Windows should be prioritized, not suspended](http://arstechnica.com/information-technology/2012/11/64-bit-firefox-for-windows-should-be-prioritized-not-suspended/)