I am just assuming based on experience and requirements for AC.
Try for example to clik a dotted line in ArchiCad 2D viewport. Then click ESC and see how long time it takes for the line to be deselected. It takes some milliseconds or even half a second.
A similar test is to draw a simple wall with no structure. Click the starting point and try to move the mouse pointer around. In Revit the line is drawn with super-high FPS, while in ArchiCad the fps seems to be much much slower. Revit appears to be "crisp" if that makes sense.
If you do this in Revit the selection and deselection is instant. Revit is definitley optimized for Quadro and Windows 2D and 3D graphics API's.
ArchiCad is optimized for OpenGL 2.0 according to the requirements. It was released in 2004.
I am in no way a Revit fan, on the contrary, but I'm a bit dissapointed with the 2D drawing experience in AC. I'm assuming it has to do with beeing architected towards OpenGL2.0, and the fact that the Mac Quartz engine isn't exactly geared towards newer standards and the new vulkan developer sets. Apple prefers developers to make AC for mantle?
Has the cross-platform architecture of ArchiCad left it stuck in an old, outdated hardware usage territory?