Issue with extruding arcs

Hello there,
I just got started with Rhino and I’m having trouble with extruded arcs. When making an extrusion for a curve in rendered mode, Rhino approximates my arc into straight curves, which is obviously not very good-looking for a rendering. I attached some photos to illustrate my problem. I tried quite a lot but do not fully understand why Rhino does this. How can I get a smooth surface on my extrusion?
Thanks in advance for any help.

Hi, could you share your .3dm file? I suppose that the issue is related to your display settings.

Have a look here:

HTH, --Mitch

Thank you very much, I could change it in the global mesh settings. The settings were probably so low because I imported a pretty detailed environment model.