Hello @Nathan, thanks for reply. Much appreciated, like always.
I think to have found a way to use raytraced Viewport without many compromises, I will also follow your advice to improve your peformance (Argh… I didn’t restart Rhino 
). Isn’t my pc, just a bit, it’s old but not so old, and it is not a Rhino perfomance issue; if anything, it’s about procedure.
This is my walkaround:
Open a File and disable Denoise in Viewport Post Pro.
Then I activate Raytraced Viewport. At this time I’m able to manage most raytraced objects, with the most complex I just have to wait a bit the automatic conversion from Nurbs to Mesh… in this case the processor is the bottlneck, but that’s all.
I hit Render… at the end of the Render, close the window… here are the problems. Difficult to move, to Rotate, to Select… I had to change View Mode to refresh Raytraced Mode and so on.
It seems that Render doesn’t realease resources after closed, so I click the little arrow at bottom left of the raytraced window to restart raytracing inside Viewport, in this way I can Move, Rotate, Select, using menu… smoothly.
Thanks a lot. Look forward for new SR.
Good job to you, I think you are busy as ever. I appreciate a lot your commitment.
Best regards to all McNeel crew,
Bartle
PS For what I know ‘XBox bar’ doesn’t record new windows, just the first one you select, so menus and rendering viewport will not be visible, but they are there