Simon Willison’s Weblog

Subscribe

5th January 2026

Research memchr-c-wrapper — Offering a pure C reimplementation of the Rust-based pymemchr, pymemchr-c delivers high-performance byte and substring search functions to Python with extensive SIMD (SSE2/AVX2/NEON) optimizations and runtime CPU feature detection. Its unique "Packed Pair" substring search algorithm enables the C version to outperform both Python's built-in methods (up to 28x faster) and the original Rust extension (up to 1.5x faster for substring operations), all while removing the need for a Rust toolchain.

This is a beat by Simon Willison, posted on 5th January 2026.

Monthly briefing

Sponsor me for $10/month and get a curated email digest of the month's most important LLM developments.

Pay me to send you less!

Sponsor & subscribe