Engineer watches Opus55 optimize a Jai rewrite: "100x slower by hand"
lucasmeijer · x · 2026-10-18
Engineer Lucas Meijer shared his reaction after reading the traces of Opus55 optimizing the Campfire Jai rewrite: the model is incredibly good at focused experiments, measuring results, and selecting opportunities worth exploring. His verdict: doing this kind of optimization work by hand is 100x slower. A high-quality firsthand account of a frontier coding model on real performance-optimization work.
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