As I work more with Cura, I see other times there are rendering issues. The menus are not the only time I see a problem. The area where the model is displayed will sometimes show two different rendering modes after I have changed the rendering style, with perhaps the right 1/3 being the old style.
I just spent several minutes playing with changing rendering styles. Switching between Solid and X-ray may take up to a minute, during which Cura is essentially locked up. But, sometimes it is nearly instantaneous. During the long pause times, at least initially, Cura is completely locked up, though I can use other applications. Often clicking on the Cura window, or a separate application's window, will cause an instantaneous display of the chosen rendering style. I understand that the layers display requires some additional processing, so the delays are understandable.
I will also mention that in the past I had tried Cura 2.4, 2.5, 2.7 all with the same issue. But, now that I understand how to manage it, I think I will continue to use the version 3.4
But, with a new version changing video rendering engines, then I certainly understand how it would not be worth the effort to investigate this further.
Thank you for checking into it. I will look forward to ver 5, and hopefully it will resolve the issue.
-Joe