Accelerating GPT-5.6 Sol Ultrafast with OpenAI

This post introduces Ultrafast Mode, a new service tier for OpenAI API powered by Cerebras, which accelerates GPT-5.6 Sol to deliver up to 750 output tokens per second. It highlights performance improvements over existing models on benchmarks like Humanity's Last Exam and GDP-Val, demonstrating a 7x speedup on HLE and a 5.6x end-to-end speedup on GDP-Val with no quality degradation. The technical innovation enabling this speed is Cerebras's Wafer-Scale Engine architecture, which packs 44GB of SRAM on-chip to keep model weights local and minimize data movement, contrasting with GPU-based approaches bottlenecked by off-chip storage transfers.