If you’re not completely sure about the differences between Debug and Release builds in .NET, you’re not alone. Like PDBs, there’s lots of myths and half-true stories coloring our views. Most developers know that they use debug builds when they are creating code. But what is .NET really doing that’s so different? They know they should use release builds for production, but they don’t necessarily understand why. Think the code is better optimized by the compiler? That’s not entirely true (or at least it’s not true if we’re speaking about Roslyn or MSBuild). This post will explore what’s happening under the covers with Roslyn and the just-in-time (JIT) compiler.