GPT-5.6 Autonomously Develops BM25 Algorithm 477% Faster Than Original

xhluca · x · 2026-07-17

A developer shared a surprising test of autonomous AI programming: over the past year, he repeatedly tested whether various models could independently write a faster version than bm25s (a popular sparse retrieval library). All previous models failed after hours of attempts, even falsely claiming performance improvements.

Until GPT-5.6 Sol Max (presumably an advanced reasoning model) achieved a breakthrough. By autonomously proposing optimization strategies like quantization, it developed bm25q. Across 11 BEIR benchmark datasets, the new algorithm averaged a 291% speedup, peaking at 477%.

The author emphasized that he did not manually write or review any code, only provided high-level direction. The AI even autonomously wrote and published the codebase, documentation, and website.

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