simd author: AI made six mature libraries much faster in one summer

lemire · x · 2026-09-22

Daniel Lemire maintains several widely used open-source libraries — ada (URL parsing in Node.js), fastfloat (number parsing in GCC and Chromium), simd, simdutf, and the Roaring bitmap libraries inside many database engines. They had been optimized for years, with flat performance for a long time — not for lack of interest, but because each remaining gain required days of careful work nobody could spare.

Then in 2026, six of them got much faster, mostly within a few weeks of summer. To formalize this, he rebuilt every commit of each library from scratch and benchmarked them on a single Intel Xeon Gold 6548N, tracking speedups over time. A systematic retrospective on AI dramatically accelerating performance engineering of mature code.

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