Mozilla's Firefox 156 release improves large JPEG handling by using libjpeg-turbo's IDCT scaling during decoding instead of loading full-size images first, cutting memory use up to 20 times and doubling decode speed. The update also makes the built-in PDF.js viewer start up to 45% faster by loading its background worker earlier, and expands sponsored address bar suggestions to France, Germany and Italy. Firefox 157, due in about two weeks, is expected to add support for the JPEG XL image format.
Mozilla's latest State of Open Source AI report, using data through September 1, finds top Chinese open-weight models are closing in on closed US frontier systems, lagging by only a few percentage points on key benchmarks while costing far less to run. The report estimates the capability gap at roughly 4.4 months based on METR task-horizon data, close to Epoch AI's independent four-month estimate, and notes one Chinese model scored within a point of a leading Claude model on Terminal-Bench at under a fifth of the price.
Mistral has struck a partnership with Mozilla under which its AI models will power Firefox's built-in AI assistant. The deal aims to broaden Mistral's reach among everyday consumers by tapping into Firefox's established user base.
Mistral AI and Mozilla announced a partnership making Mistral's models power Firefox's beta AI browsing assistant, Smart Window, which helps users navigate searches, recall browsing history, and pull information from open tabs. The rollout starts in France and North America, with the UK and Germany planned later this year.
Mozilla worked with Lincoln Loop and a designer to rebuild Firefox.com entirely in modern, native CSS, skipping preprocessors like Sass. The new system exports custom properties directly from design files and includes over 70 components and 25 page templates built as Wagtail components, supporting 19 locales.
Mozilla worked with Lincoln Loop and a design lead to rebuild Firefox.com using only modern, native CSS, dropping preprocessors like Sass entirely. The project exported custom properties straight from design files and used CSS Grid and Flexbox, building a system of more than 70 components and 25 page templates as Wagtail components so non-engineers can assemble pages. The site now supports 19 locales, with a lightweight branded stylesheet ensuring older browsers still get basic accessible styling.
Mozilla's State of Open Source AI report finds that leading open-weight models like Moonshot AI's Kimi K3 now score nearly as well as closed frontier models such as Anthropic's Fable 5, while costing roughly 30 percent as much. The report argues most organizations should default to open models for routine tasks, reserving costlier closed models for specific high-stakes workloads.
A new State of Open Source AI report from Mozilla, shared with Ars ahead of its September 15 release, finds that top open-weights models from Chinese developers now perform nearly on par with closed frontier models from US firms like Anthropic and OpenAI. It cites Moonshot AI's Kimi K3 scoring only three points below Anthropic's Fable 5 on the Artificial Analysis Intelligence Index, despite costing roughly 30 percent as much to run.
A follow-up Wireshark analysis of Firefox 155 confirms an earlier finding: toggling off Mozilla's AI kill switch disables generative AI features but does nothing to stop background telemetry or advertising data collection. The retest comes six months after Mozilla's CEO publicly called the AI switch one of the browser's most important features, even as onboarding flows never mention what the control actually covers.
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