Version 54.0, first offered to Release channel users on June 13, 2017
Today's release is the first to run Firefox using multiple operating system processes for web page content, making Firefox faster and more stable than ever. Learn more about how multiple processes strike a “just right” balance between performance and memory use on the Mozilla Blog. Dive into the details (including performance benchmarks) on Medium.
We'd also like to extend a special thank you to all of the new Mozillians who contributed to this release of Firefox!