Please keep in mind that Rhino V7 is intended for Intel CPU Macs, not Silicon CPU Macs.
We are all relying on the Apple provided software translation layer called Rosetta. It’s a lot better than nothing, but it’s not great for performance or for OpenGL graphics reliability.
For straight up surface modeling, this compromise setup seems to work fairly well. Rendering is frustratingly slow as you well know.
The fix will be Rhino V8, which when released, will support Mac Silicon processors natively without “Rosetta”, and will use the new “Metal” display language. We expect to finish development and release V8 sometime next year.
We anticipate Rhino performance to be quite good.
Since you own a V7 license, I encourage you to download a try the V8 Work-In-Progress builds. While incomplete, it will perform much better that V7 relying on Rosetta.
For additional discussion on this issue: