if I open the Rhino options and set something on one of the categories or only I look at one and close the dialog, than some times Rhino starts a remeshing of the display mesh, because it is reset to “jagged and faster”. This is a very old bug reported some years before.
For complex models it cost some time to get the render mesh back. I hope it’s on the time to catch this bug.
(I use Rhino 6 English on Win 10 64 German.)