OpenAI Codex Ultrafast: 8x Faster, But It Can Burn Your Weekly Limit in 2 Hours

OpenAI Codex Ultrafast: 8x Faster, But It Can Burn a Week's Usage Limit in 2 Hours

You pay $500 a month so Codex can code faster, then discover that after just 2 hours of work, your entire weekly usage limit is gone. That is exactly what one programming YouTuber just experienced with OpenAI's newest feature, Ultrafast.

What Is Ultrafast

Ultrafast is a premium speed tier that OpenAI announced at DevDay 2026 (September 29), applied to the GPT 6 Astra model inside Codex, the command line tool that lets AI write and fix code for you. With Ultrafast turned on, Codex responds up to 8 times faster than normal speed, roughly 300 tokens (the text units AI processes) per second. Through the API for developers, the speed boost is a bit lower, around 6 times.

This feature is only available on the Pro 500 plan, the $500 a month tier that OpenAI launched right after DevDay. The two cheaper plans, at $100 and $200, do not include Ultrafast.

The Real Cost Behind the Speed

Speed is not free. Theo, a YouTuber who reviews AI coding tools on the channel t3.gg, shared that he spent $600 just to have Ultrafast review two small pull requests, meaning two small code change packages waiting to be merged into a project. In another video, he said the Pro 500 plan's weekly usage limit can disappear in about 2 hours if Ultrafast is used continuously.

The reason comes down to how usage is charged. Ultrafast does not bill at the normal rate, it multiplies it by 6 to 8 times. For the GPT 6 Astra model, Ultrafast's API price is $60 per 1 million input tokens and $300 per 1 million output tokens, far above the standard rate. On Codex, every minute spent on Ultrafast consumes plan usage limit 8 times faster than normal speed. In other words, you do not pay extra cash at that moment, but your weekly limit drains far faster.

Is the $200 Plan Still Worth It

The question Theo raises in his video is this: if the real speed advantage only exists on the $500 plan, is the $200 plan still worth using? His view is that Ultrafast's extreme speed is genuinely useful when you need instant feedback to stay in flow while coding, but because the hidden cost is so large, it fits urgent moments better (for example, fixing a production bug that is causing an incident) rather than being left on all day.

What This Means If You Are Vibe Coding

If you are teaching yourself vibe coding, meaning having AI write most of the code instead of typing it yourself, here are a few things worth remembering:

• Do not turn on the highest speed by default. Codex's normal speed is already fast enough for most daily work. Only consider Ultrafast when you are genuinely waiting on an urgent change.
• Check your usage limit regularly, do not wait until the end of the week to find out you have used it all up.
• Compare before upgrading your plan. If your work does not need instant speed, a cheaper plan is still enough.
• Claude Code takes a different approach. If you are used to Claude Code, Anthropic has not introduced a similar multiplied-rate speed tier so far, which is a difference worth weighing when choosing a tool.

Limitations to Keep in Mind

The cost figures in this article come from Theo's own real world experience shared in his videos, not an official OpenAI announcement of exact usage costs for each type of task. Your actual cost may vary depending on the type of task, the length of the conversation, and the amount of code being processed.

Frequently Asked Questions

Is Ultrafast available on the free Codex plan or cheaper plans? No. At launch, Ultrafast is only available on the Pro 500 plan ($500 a month) or purchased separately through the API.

Does using Ultrafast cost extra money right away? On the Pro 500 plan, you do not pay extra cash immediately, but your weekly usage limit gets deducted 8 times faster than at normal speed.

How much faster is Ultrafast than normal speed? Up to 8 times faster in Codex (about 300 tokens per second) and around 6 times faster through the API.

Should you upgrade to the $500 plan just for Ultrafast? Based on Theo's experience, it is only worth considering if your work regularly needs instant feedback. For most people learning vibe coding, normal speed is still enough.

Does Ultrafast apply to every OpenAI model? No. Ultrafast currently only applies to the GPT 6 Astra model, while other models such as 6.1 Sol are still gradually getting support added.