Which material previews are available? Have no - use C4D-Standard!
Hi @HarrySeidl
As previously mentioned here, the Cinema 4D previews are fully supported natively by V-Ray. We will be adding our own previews in the future but it is totally fine to use the Cinema 4D ones.
Thanks!!! 
Hi guys, I’ve got a problem with material preview. I try to use R21 and Vray-5.00.42 from Dec 10 (WIN10)
When I create a material, Cinema will become very very slow and I cannot see the material preview.
I’ve got a Nvidia GeForce GTX 1070.
Anyone has got the same problem? How can I fix? Thank you
UP: Fixed
Hi everbody, it is so hard to work with this very slow material-previews - I deactivate the preview, but this is also hard to work… Please, please solve it!!! LG
Hello,
This issue has previously been discussed in other threads in the forum and we are aware of it. You can find a discussion about it here. We will be working on implementing a fix for it. Thank you for your understanding.