I have been doing a lot of research this week on WPF performance issues, and I have run across many blog posts that suggest that the calculation of the rendering tier value for a WPF-enabled target platform is based solely on the version of DirectX installed on the target. That’s not quite the whole story. The minimum software and hardware requirements for each tier are as follows: Rendering Tier DirectX Version Video RAM Pixel shader Vertex shader Multitexture units 0 Older than 7.0 - - - - 1 Between ......