64-bit Firefox for Windows should be prioritized, not suspended
The stable, supported, mainstream version of Firefox on Windows is a 32-bit application. Even if you use 64-bit Windows, if you use Firefox, you're using a 32-bit browser. The exception is if you're using the Nightly build of Firefox. This represents the latest, cutting-edge version of the browser, and it's available in two versions: a 32-bit one, and a 64-bit one.
However, this won't last much longer. Mozilla announced last week it was no longer going to produce 64-bit Nightly builds of Firefox for Windows; nor will it run automated tests of 64-bit Firefox. The browser's future on Windows is resolutely 32-bit. Linux and Mac OS X, in contrast, both have official 64-bit versions.