An anonymous reader writes: Mozilla today launched Firefox 57, branded Firefox Quantum, for Windows, Mac, Linux, Android, and iOS. The new version, which Mozilla calls "by far the biggest update since Firefox 1.0 in 2004," brings massive performance improvements and a visual redesign. The Quantum name signals Firefox 57 is a huge release that incorporates the company's next-generation browser engine (Project Quantum). The goal is to make Firefox the fastest and smoothest browser for PCs and mobile devices -- the company has previously promised that users can expect "some big jumps in capability and performance" through the end of the year. Indeed, three of the four past releases (Firefox 53, Firefox 54, and Firefox 55) included Quantum improvements. But those were just the tip of the iceberg. Additionally, Firefox now exclusively supports extensions built using the WebExtension API, and unsupported legacy extensions will no longer work, the company said.