Mirror tiles

Hey
I have just updated to Rhino 6, and the new Flamingo nXt. But I am sadly not very happy about it!
-the rendering is running very slowly, and I cannot find the “Mirror tiles” box, when I am trying to create my own materials.
Can you help me to find the box where I choice “Mirror tiles”?

Best regards Anita

I’m beginning to think McNeel doesn’t care about this. I am now working in Rh 6, but saving a file to render in Rhino 5 format, just to use the older Flamingo.

Frustrating…

Bob? You listening?