NVIDIA's GameWorks Blocking AMD From Optimizing?
 

Can't we all just get along? In Nvidia's GameWorks program, though, all the libraries are closed. You can see the files in games like Arkham City or Assassin's Creed IV — the file names start with the GFSDK prefix. However, developers can't see into those libraries to analyze or optimize the shader code. Since developers can't see into the libraries, AMD can't see into them either — and that makes it nearly impossible to optimize driver code.

http://www.hardocp.com/news/2013/12/...ptimizin g63/