Update: I've tested the file on other computers now (better specs than my office desktop), and tend to think that it's a combination of the large image (surface) coupled with whatever OpenGL programming/drivers within ArchiCAD. Results are the same: everything works fine in AC15, but both 'show' and 'save' are still significantly slower if not unusable. With simpler surfaces they work better in AC16,AC17 but still not as smooth as in AC15.
The main reason I'd like this to work better in 17 is because the BIMx (17) can now adopt 1 path as a smooth video, rather than previous versions where you had to record a path live in BIMx; this method would always yield jumpy vids unfit for presentations. In order to set it up in the AC17 file I would need to 'show' it several times over to edit the path and camera focal points for best results.
Tech support is next step.
Win 10 Pro, Threadripper 1950x 16-core, 32GB RAM, RTX 3080Ti 12GB GRAM