Claude Opus 5.5 gets fast mode, but only at extra cost

What's new

Anthropic has made fast mode available for Claude Opus 5.5. It can be switched on in the coding tool Claude Code and on Claude Platform. It is not a new model, but the same Opus 5.5 run with a setting that prioritizes speed. Responses arrive up to 2.5 times faster.

The most important point for everyday users is that fast mode is not included in the subscription. Even if you have a Pro, Max, Team or Enterprise plan, fast mode is billed against so-called usage credits. These are a kind of extra usage credit that you have to turn on yourself. They are charged even if you have unused capacity left in your subscription. The feature is a "research preview," so it and its price may change.

What's smart about it

The quality is the same. You get the same model and the same capabilities, just faster. That is useful when you are sitting and waiting for answers, for example when you are fixing code over and over or debugging live.

It is turned on with the /fast command in Claude Code, and VS Code has a corresponding button. The price is the same across the entire context window of 1 million tokens (chunks of text). If your credits run out, Claude Code automatically falls back to normal speed and normal pricing, so your work does not stop.

Cheaper or better?

It is not cheaper. For API use, fast mode on Opus 5.5 costs $8 per million input tokens and $40 per million output tokens. According to independent outlets, regular Opus 5.5 costs $4 and $20, so fast mode is roughly twice as expensive. By comparison, fast mode on the older Opus 5 and Opus 4.8 costs $10 and $50, which makes Opus 5.5 the cheapest fast option.

There is a small catch: the first time you turn on fast mode in a conversation, you pay the fast-mode price for all the text already in the conversation. So turn it on at the start. The monthly cost for everyday users is not fixed, since it depends on usage. The sources do not compare it with competitors' fast modes.

Who it's good for

Fast mode suits work where you sit and wait: quick code fixes, troubleshooting and tasks with tight deadlines. For long tasks that run on their own, for large batch runs and for work where price matters more than speed, normal mode is the smarter choice.

In Team and Enterprise, the feature is off by default. An owner has to switch it on first, and the company pays from its credits. It is not available through Amazon Bedrock, Google Cloud or Microsoft Foundry. The sources do not say whether it is aimed specifically at Denmark or the EU.