Firefox 156 Speeds Up PDF Loading by 45% and Adds a macOS Autostart Option

The official Firefox 156 release notes state that Mozilla has released Firefox 156.0, which includes faster PDF loading, reduced resource consumption when displaying large JPEG images, a new macOS startup option, and a number of fixes. Firefox 156.0 was made available to users on the Release channel on September 15, 2026. The built-in PDF viewer is now up to 45% faster to start up, and the browser uses less memory and CPU when showing large JPEG images that have been scaled to fit a page.