(Extended Support Release) is a special version of Mozilla Firefox released in June 2018 . It represents the final build of the Firefox 52 ESR cycle, which began with version 52.0 in March 2017.
This version utilizes the older, single-process architecture before Firefox transitioned to the multi-process "Quantum" engine. It requires significantly less RAM and CPU power, making it ideal for computers with less than 2GB of RAM. Critical Security Warning firefox version 52.9. 0 esr download