As the Product Manager for Firefox Desktop, I was charged last year with
investigating what it would mean for Mozilla to ship an official release
of Windows 64-bit Firefox.
You can see much of the results of that investigation in these two
earlier mozilla.dev.planning threads:
*Firefox 64-bit for Windows: data gathering*
*Firefox 64-bit for Windows: what we know*
Having completed that investigation, including consulting with many
leaders across the Mozilla project, I've concluded that now is not the
right time to promote the 64-bit Windows 7 builds from their current
status as "experimental" to "supported release" status.
We have many challenges in front of us that require considerable and
immediate effort. While there are advantages to making Windows 7
64-bit builds available to a wider audience, it's my evaluation that
doing so should not be a priority today. I recommend that Mozilla wait
until we've finished other higher priority work before investing the
considerable resources necessary to uplift that build to a supported
There is a very good chance that we will want to transition capable
systems to 64-bit Firefox builds for Windows 7 (and newer Windows
versions) at some point in the not too distant future -- right now I'm
thinking early next year. That likelihood, and the work that's already
been done to get 64-bit build and test infrastructure stood up and
running, has convinced me that we should continue to support 64-bit
experimental nightly builds until such time that we can afford the
resources and prioritize the remaining work.
Keeping the 64-bit nightly builds functioning at the level they are
today will help to ensure that when we do dive into the remaining work,
we won't have to repeat work that's already been done. In addition to
that, providing nightly builds allows some of our more demanding core
contributors, those who regularly keep dozens or even hundreds of tabs
open, to continue to use Firefox as their primary browser.