Claude Fable 5's performance in multiple tests sparks widespread discussion According to 10 test cases compiled by developer @deedydas, Fable 5 completed a full library migration of Stripe's 50 million-line Ruby codebase in 1 day—something that would take a human team 2 months to finish. It can render a 3D simulation of over 5,000 objects in real-time within a browser, including realistic forest scenes and the New York skyline. Cleared Pokemon FireRed in one go. In interactive network evaluations for real-world business scenarios, its efficiency is 10x higher than GPT 5.5. In the FrontierCode benchmark for code quality, Fable 5 also scored higher than other cutting-edge models, even with moderate computing power.