Inside the Fastest C++ Library Ever - Breaking the 200ns Barrier! - Larry Ge - C++Online 2026

A conference talk presenting Nexus Fix, an open-source MIT-licensed C++23 FIX protocol parsing library targeting sub-200ns execution latency. The speaker walks through five key optimization techniques: SIMD-based two-stage parsing (AVX2/AVX512 with runtime hardware detection), PMR (Polymorphic Memory Resources) to eliminate heap allocations and reduce P99 spikes by ~14x, structural indexing for O(1) field access instead of O(n*k) scanning, Simple Binary Encoding (SBE) flyweight pattern for 5.5x decode speedup, and lock-free deferred processing via an MPSC queue to offload non-critical work like checksums and logging off the hot path. Additional gains come from `std::assume_aligned` hints and C++23 features including `consteval`, concepts replacing SFINAE, compile-time string hashing, and `std::expected` for deterministic error handling. Combined, these techniques achieve a 33x improvement over QuickFIX baseline (from ~5000ns to ~143ns), with P99/P50 ratio reduced from >10x to <1.5x.