Performance Optimization

Most performance problems in C# aren't where you think they are. The slowest line of code is rarely the one that looks suspicious; it's the innocent-looking LINQ chain in a hot loop, or the string concatenation that allocates a few hundred megabytes over an afternoon. This chapter is about finding those costs with real measurements, then fixing them with the tools the runtime gives you: Span<T>, stackalloc, ArrayPool<T>, value types, and a handful of patterns that keep the garbage collector out of your way.