I dont think this is Cerebras. Running on cerebras would change model behavior a bit and it could potentially get a ~10x speedup and it'd be more expensive. So most likely this is them writing new more optimized kernels for Blackwell series maybe?
OpenAI in my estimation has the habit of dropping a model's quality after its introduction. I definitely recall ChatGPT 5.2 being a lot better when it was introduced. A week or two later, its quality suddenly dropped. The initial high looked to be to throw off journalists and benchmarks. As such, nothing that OpenAI says in terms of model speed can be trusted. All they have to do is lower the reasoning effort on average, and boom, it becomes 40% faster. I hope I am wrong, because if I am right, it's a con game.
It's good to be skeptical, but I'm happy to share that we don't pull shenanigans like this. We actually take quite a bit of care to report evals fairly, keep API model behavior constant, and track down reports of degraded performance in case we've accidentally introduced bugs. If we were degrading model behavior, it would be pretty easy to catch us with evals against our API.
In this particular case, I'm happy to report that the speedup is time per token, so it's not a gimmick from outputting fewer tokens at lower reasoning effort. Model weights and quality remain the same.
It looks like you do pull shenanigans like these [0]. The person you're replying to even mentioned "ChatGPT 5.2", but you're specifically talking only about the API, while making it sound like it applies across the board. Also appreciate the attempt to further hide this degradation of the product they paid for from users by blocking the prompt used to figure this out.
Hey Ted, can you confirm whether this 40% improvement is specific to API customers or if that's just a wording thing because this is the OpenAI Developers account posting?
Then from that they realized they could just run API calls more like staff, fast, not at capacity.
Then they leave the billion other people's calls at remaining capacity.
https://thezvi.substack.com/i/185423735/choose-your-fighter
> Ohqay: Do you get faster speeds on your work account?
> roon: yea it’s super fast bc im sure we’re not running internal deployment at full load
In the past month, OpenAI has released for codex users:
- subagents support
- a better multi agent interface (codex app)
- 40% faster inference
No joke, with the first two my productivity is already up like 3x. I am so stoked to try this out.
In this particular case, I'm happy to report that the speedup is time per token, so it's not a gimmick from outputting fewer tokens at lower reasoning effort. Model weights and quality remain the same.
Happy to retract if you can state [0] is false.
[0] https://x.com/btibor91/status/2018754586123890717