Well, it is not a compatibility issue. And yes, there are other cards that suffer performance problems when running shaders. We cannot alter the designed performance limitations of a video card. In general, the FX5xxx series executes shaders rather poorly, but it is a design problem with the architecture.
This has been well documented all over the Internet. Check any game forum and ask about it.
Due to the issues with shader performance with many cards, there is a check box to disable this. That is how you get around the performance problem.
Cards that do not suport T&L, do not even have the option of running shaders.