Resolved an issue where certain add-ons were incorrectly registered with Firefox's multiprocess architecture, leading to incompatibility. Download and Legacy Status Firefox for Windows 64-bit
32-bit applications use less RAM per process compared to their 64-bit counterparts, making them suitable for machines with 4GB of RAM or less. How to Download Safely download firefox 51.0.1 32 bit
It is the primary version for older operating systems like Windows XP (SP2) and Windows Vista , as Firefox 53 later dropped support for these platforms. Resolved an issue where certain add-ons were incorrectly
Once installed, you should tweak a few settings to maximize performance on 32-bit systems: download firefox 51.0.1 32 bit
https://ftp.mozilla.org/pub/firefox/releases/51.0.1/win32/en-US/Firefox%20Setup%2051.0.1.exe