Something I neglected to mention about the recent Firefox 43 release: there is finally an official, 64-bit version of the browser. There have been unofficial and/or experimental 64-bit versions in the past, but they were abandoned for various reasons and never made it to prime time.
Those of you with modern computers who are running a 64-bit operating system have the option of installing the 64 bit Firefox or sticking with the traditional 32-bit version. The two versions look and act exactly the same, and I don’t think it’s likely that any particular advantage will be gained by switching to the 64-bit version. However, some people (you know who you are) are excited about this long-promised Firefox version.