Rico Mariani gave a talk based on a paper on .NET performance. It’s mostly what you’d expect from a managed runtime. Over here someone took the time to detail the performance of most IL instructions for .NET 1. The exact perf numbers don’t matter so much as the magnitude. I wonder if lambdas in C# 3.0 are still as expensive as delegates (8X more than an instance call). I do wish someone would explain when the JIT will inline code. This could go a long way towards writing more efficient libraries. The thing about performance is that it’s more than merely learning to use a language/runtime. It’s also about conforming to the style and expectations of the language/runtime implementors.