fast-mode.md Claude Code Docs, 2026-04-15 04:00 UTC → 2026-05-02 04:05 UTC

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13Fast mode is a high-speed configuration for Claude Opus 4.6, making the model 2.5x faster at a higher cost per token. Toggle it on with `/fast` when you need speed for interactive work like rapid iteration or live debugging, and toggle it off when cost matters more than latency.13Fast mode is a high-speed configuration for Claude Opus 4.6, making the model 2.5x faster at a higher cost per token. Toggle it on with `/fast` when you need speed for interactive work like rapid iteration or live debugging, and toggle it off when cost matters more than latency.

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15Fast mode is not a different model. It uses the same Opus 4.6 with a different API configuration that prioritizes speed over cost efficiency. You get identical quality and capabilities, just faster responses.15Fast mode is not a different model. It uses the same Opus 4.6 with a different API configuration that prioritizes speed over cost efficiency. You get identical quality and capabilities, just faster responses. Fast mode is not available on Opus 4.7 or other models.

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17<Note>17<Note>

18 Fast mode requires Claude Code v2.1.36 or later. Check your version with `claude --version`.18 Fast mode requires Claude Code v2.1.36 or later. Check your version with `claude --version`.