Architectural Patterns for a 5.5M msgs/sec Market Data Parser in C++20 Processing raw market data feeds (like NASDAQ ITCH 5.0 or NSE FO) requires strict adherence to low-latency principles. Recently, I built a C++20 parser to ingest these feeds, normalize them, and manage a Limit Order Book (LOB). By strictly controlling memory allocation and maximizing CPU cache locality, the parser achieves a throughput of ~5.5 Million messages/sec (169 MB/s) on an Apple Silicon (M-Series) processor, with a P50 latency of 84 nanoseconds per message. This write-up covers the three primary technical patterns used to achieve this throughput. High-Performance Market Data Parser A production-grade, low-latency C++ market data engine designed for High-Frequency Trading (HFT) applications. It ingests raw exchange feeds (NASDAQ ITCH 5.0, NSE FO), standardizes them efficiently, and maintains a clean Limit Order Book (LOB) State of the World.…