why mac pro not supported in windows operating system

How do you have windows installed? Is it through Boot camp or through a visualisation program such as VMware Fusion or Parallels?

If it is through bootcamp you need to make sure you have installed the drivers. This might cause slowdowns.

If you are using Fusion/Parallels then check you are running the latest versions however there is quite a lot of system overhead which will cause the rendering times to be slower and may cause the problem you are talking about. If you are using this method it might be worth trying to use bootcamp for this purpose.

 

Why do you use Windows? Get a version of Maya for OSX.