Firefox users have reported sudden spikes in CPU usage and battery drain that appear to be linked to a background task labeled "Inference," which was introduced with recent on-device AI features. The highest-profile culprit is the browser's new AI-assisted tab grouping, a function that reads open tab titles and suggests group names and related tabs using a local model. People who opened Firefox's process monitor and profilers noticed that the Inference process was consuming large amounts of CPU, making fans run loudly and laptops lose charge far faster than during normal browsing. Mozilla says the feature was rolled out in phases, acknowledged an unintended performance regression after receiving user reports, and reversed the rollout while engineers work on a fix.

If this is happening to you there are several ways to check and mitigate it right now. Type about:processes to see which Firefox processes are active and how much CPU they use, and use about:config to turn off the related experiment flags. Relevant preferences include browser.ml.enable, browser.ml.chat.enabled and the smart tab grouping keys such as browser.tabs.groups.smart.enabled. Unticking the AI chatbot or disabling those keys should stop the local inference activity without affecting basic browsing. Mozilla frames these capabilities as privacy-minded, on-device tools designed to avoid sending data to servers, but the episode shows the risk of introducing new machine learning features to a wide user base before they are fully mature. Users who continue to experience problems are advised to file a performance bug with a profiler capture, so the developers have the necessary data to track down the root cause.