I have programmed against all versions of Windows since 3.1, so yes, I realise quite a lot about the OS. Yes, the .NET controls are mostly wrappers around the Win32 ones. That is obvious, the APIs are so similar they haven't even fixed some of the obvious problems. I ask you (rhetorically, mainly) where would the speed difference come from? The native interop? What about if the controls were written purely in .NET? It's a JIT language -- by the time the code is running, it's been compiled to native code. The memory difference is correct, but that could certainly be minimized -- by caching the compiled stuff, mainly. There is nothing inherently inefficient about systems like .NET. If Microsoft wanted to use .NET more, they would fix these issues, they aren't fundamental problems with the platform, they're more just implementation issues in the current version. I know those controls (TreeView, ListView etc) aren't efficient because I've used them, and programmed using them. You can get around some of the issues, but it's pretty easy to stuff up. Native code or not -- it's irrelevant here; you're the one who thinks native code stuff is faster. Someone can program badly in any language, and the effect is pretty much the same.