Claude Code /fast: Toggle Fast Response Mode When in a Hurry

It's frustrating when the AI takes its time over even a light question. Conversely, it's also a problem when it rushes through something important too carelessly. /fast is a command that lets you turn this speed on and off to control it. Fast when you're in a hurry, off when you need to be careful.

Definition (what it is)

/fast is a command that toggles fast response mode on and off (a toggle alternates on/off like a switch).

Turn it on and answers come back faster. It's useful for quickly knocking out light, simple tasks.

How to use it (by difficulty)

Basic — turn on and off

/fast on

Entering this turns on fast mode. To turn it off, enter it as below.

/fast off

Common pitfalls (only when applicable)

• Fast mode is a setting that prioritizes speed. For complex tasks that need precision, it's safer to turn it off.
• Once you turn it on, it stays applied until you turn it off. It's a good habit to check whether it's currently on before entering an important task.

Real-world example

When several simple questions come one after another, handle them quickly with /fast on. Then when you enter a stage that needs tricky design or careful review, turn it off with /fast off and proceed slowly.

Taking it further

The key is being able to change speed to fit the situation. If you separate "how quickly" as /fast and "how deeply to think" as /effort, you can combine the two commands without confusing them.

Summary

/fast is a toggle command for turning fast response mode on and off. on when you're in a hurry, off when you need precision. Change speed to fit the nature of the task.

Based on Claude Code v2.1.154 (2026.05)