Grok 4.5 ranked first on speed and cost in a comparison test in which four AI coding models were asked to build apps using the same prompt. TryAI compared output quality, latency and costs for Grok 4.5, GPT-5.5, Claude Opus 4.8 and Claude Fable 5. Claude models performed best on a 3D Rubik’s Cube task, while GPT-5.5 led on a particle gravity sandbox. Grok 4.5 showed the clearest speed and cost advantage.

Some ChatGPT users have reported simultaneous performance improvements and response delays, fuelling speculation that OpenAI is privately testing GPT-5.6. Posts on X described results that appeared different from GPT-5.5 Pro on paid accounts, including better web design and 3D game outputs but much longer processing times. Developers and influencers shared comparisons, while other tests found no clear advantage. OpenAI has not confirmed anything, and the model’s release remains uncertain.