In between I installed the trial version of Poser 12 and there is the same issue. Slowing down the material editor as soon I make the newest updates of windows 10. So not even Poser 12 is the solution. But It works again if I uninstall the KB5000808 security update again.

I tested this now on 3 different PCs 2 PCs with AMD processors and 1 Notebook with Intel i7. On the notebook the Installation is also without any scripts or plugins. But Poser support want to tell me I am the only one with this issue? Maybe the issue is no problem if you have just loaded 2 figures and a cube. But in complexer scenes poser is not usable anymore. When I think how fast Blender is I realy just can say, so let Poser die, if the support is to leazy to take care of this problem. I definitely don't bother with it for much longer and concentrate on the future with DAZ and Blender