21 GB/s CSV Parsing Using SIMD on AMD 9950X

Sep 0.10.0 was released April 22nd, 2025 with optimizations for AVX-512 capable CPUs like the AMD 9950X (Zen 5) and updated benchmarks including the 9950X. Sep now achieves a staggering 21 GB/s on the 9950X for the low-level CSV parsing. 🚀 Before 0.10.0, Sep achieved ~18 GB/s on 9950X. See v0.10.0 release for all changes for the release, and Sep README on GitHub for full details. In this blog post, I will dive into how .NET 9.0 machine code for AVX-512 is sub-optimal and what changes were made to speed up Sep for AVX-512 by circumventing this, showing interesting code and assembly along the way, so get ready for SIMD C# code, x64 SIMD assembly and tons of benchmark numbers. However, first let’s take a look at the progression of Sep’s performance from early 0.1.0 to 0.10.0, from .NET 7.0 to .NET 9.0 and from AMD Ryzen 9 5950X (Zen 3) to 9950X (Zen 5), as I have also recently upgraded my work PC. Sep Performance Progression The benchmark numbers above are for the package assets CSV ... Read full article.