So how do you quickly concatenate strings?

A deep dive into efficient string concatenation in C++, benchmarking naive operator+ chaining, std::format, std::stringstream, and manual reserve+append approaches. The author introduces the simstr library's 'string expression' technique, which builds a lightweight chain of stack-allocated reference objects at compile time, calculates the total length once, allocates a single buffer, and materializes all parts in one pass. Benchmarks show this approach outperforms even manually optimized code by ~20%, while keeping the syntax as simple as JavaScript-style string addition.