C# Lowering: The Compiler Magic Behind Your Code

This article is based on official sources, compiler code exploration, experimentation using decompiler tools, and real-world experience. Have you ever been told that a for loop is faster than a foreach , or that yield return is slow because it hides a state machine underneath? In modern C#, these differences are often negligible. But over a decade ago, I remember a specific question from my first interview for a Junior Software Engineer — "Is string interpolation $"Hello, {name}"; slower than st