As of June 29, 2026, fast mode is not available on Claude Opus 4.6 (platform.claude.com)

Anthropic has announced that as of June 29, 2026, the "fast mode" feature will not be available on Claude Opus 4.6. This mode, which significantly boosts output token generation by up to 2.5 times on models Claude Opus 4.7, 4.8, and 5 at a premium rate, allows users to opt-in via specific API requests. However, Claude Opus 4.7 will be deprecated, and participants using this version must migrate to 4.8 to continue enjoying enhanced speed. Fast mode is still available for the other models in research preview and offers a dedicated rate limit system. This announcement is significant for the AI/ML community as it highlights the evolving landscape of AI model capabilities and pricing structures. The fast mode provides substantial performance upgrades, crucial for applications needing quick responses, such as chatbots or real-time data processing. Key technical implications include the need for users to adapt their implementations based on model availability and pricing, as well as the critical importance of monitoring API usage to avoid exceeding rate limits, which can result in errors and affect productivity.