Raytraced mode is becoming better and better, but there are still some kinks that needs to be ironed out for it to be a modern experience.
1- Slow GUI
Selecting a new display mode while raytraced is calculating is a bit of a pain as Rhino often just picks the one underneath the mouse cursor (even if I don't click the button) when a new cycle is calculated. And the entire selection thing is a slow affair. I use Raytraced in CPU mode since the i7 is much faster than the old geforce 750m, so I guess there should be some better multitasking going on. 8 threads should be plenty for Rhino to both handle background rendering and smooth GUI navigation.
2- Independent viewports.
Having Raytraced on when modelling is too slow as Raytraced tries to update whenever a change is made, but when doing so it hogs the resources and makes modelling really slow. Here Rhino should update Raytraced independently from the other display modes.
(3-) Editing materials should also be independent of the raytraced mode, so we can continue tweaking as fast as we like, and then Raytraced can catch up in its own speed.