Is there a way to purge unused materials or shaders that you placed in your scene once, but changed your mind and are no longer using it in a scene? I have a simple scene however my shader pull down is gigantic, can I save only the ones that are being used?

You can try to navigate to the Scripts->Utilities directory in the content library tab and use "purge memory" and see if that helps.

Thanks I will try that. The file takes forever to load with all this unused stuff.