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Turn on Fast mode
Fast mode makes Claude Code and Codex respond faster on supported models, at a higher cost to your plan or bill. Turn it on when waiting slows you down.
Fast mode makes the agent answer sooner. Anthropic says it doesn’t change the quality of Claude’s answers. It costs more, so it suits short back-and-forth work more than long tasks you leave running.
Before you start
- Use Claude Code or Codex. Grok Build, OpenCode, and Antigravity don’t have Fast mode.
- Claude Code: Fast works only on some Claude Opus models. On a Claude plan it’s paid from usage credits rather than your plan’s included usage, so usage credits must be turned on in your Claude settings. Team and Enterprise plans also need an owner to turn Fast on for the organization. See Anthropic’s Fast mode guide.
- Codex: Fast works on supported models when Codex is signed in with ChatGPT, and it uses up your plan’s limits faster. With an API key, Codex charges API prices instead of using your plan’s limits. See OpenAI’s speed guide.
Steps
Open the agent settings
At the bottom of the message box, select the agent button.
Select Fast in the Speed column
Point to Fast to read what it costs with your agent.
Send your message
The agent button shows Fast with a lightning bolt while it’s on.
To turn it off, select Standard in the Speed column. In the iPhone app, select the button that shows the model and effort, then turn Fast mode on or off.
Good to know
- Fast stays on in that conversation until you turn it off, and new conversations start with the speed you used last in the project.
- When you switch to another agent, speed goes back to Standard, unless that agent used Fast earlier in the same conversation.
- Fast and effort are separate. Lower effort means less thinking, while Fast keeps the same thinking and answers sooner. You can use both together.
- A preset can include Fast mode, so one selection turns it on with your other settings.
If something goes wrong
Fast mode is unavailable for this model or account
Claude Code couldn’t turn Fast on. Choose a model that supports it, or turn Fast off. If your plan needs usage credits for Fast, turn them on in your Claude settings.
Claude could not turn Fast mode off
Enjoy didn’t send your message. Try sending it again.
Fast is grayed out
The selected agent doesn’t have Fast mode, so Fast can’t be selected. Switch to Claude Code or Codex to use it.