I have been using Autodesk Inventor since version 9 for moderate size assemblies. Like probably many users of 3D CAD software, I was always struggling with performance. My edits and drawing views were updating quite slowly.
Now I am using Inventor 11 and my company bought me a new workstation at the end of the last year – HP xw4400 with Intel Core 2 Duo processor @2.4GHz. As I understand it, Inventor 11 is not a multi-threaded application. That’s why I was surprised to find how much faster is Inventor running now compared to similary equipped single-core machine. Both assembly editing and drawing view regens are much faster. Windows is probably distributing systems tasks between both cores freeing more power for Inventor itself.