Accelerating GPT-5.6 Sol Ultrafast

Cerebras and OpenAI have introduced Ultrafast Mode, a new service tier for the OpenAI API, powered by Cerebras. This mode, initially available to select customers, accelerates GPT-5.6 Sol to deliver up to 750 output tokens per second without compromising quality. In evaluations, GPT-5.6 Sol on Ultrafast mode answered 2,500 HLE questions in 11 hours and 11 minutes, nearly 7 times faster than Claude Fable 5, which took 78 hours and 27 minutes for the same task.