This is entirely unrelated to HMH, but there's enough collective knowledge here that perhaps someone can help my understanding :)
I've been trying to understand the performance profile of 3D rendering in OpenGL. I seem to be encountering frame drops when rendering reasonably high poly meshes - but only when those meshes occupy a large portion of the screen. If I shrink the viewport, or if the object is far enough away that it doesn't occupy most of the screen - it's absolutely fine.
For some time I suspected this was a symptom of being fill-rate limited.. especially since the issue goes away if I reduce the viewport size (it stands to reason that if it's rendering to a smaller area, we're not trying to fill so many pixels or perform so many texture lookups).
I have discovered that the issue remains even after disabling textures.. and lighting.. and drawing the mesh as a solid colour. I also get no benefit from drawing as a wireframe, rather than filled. In fact, the frame drop issue remains even with the most braindead vertex/fragment shaders.
So it would seem that the issue clearly isn't fill-rate. I must be pushing too much geometry. But that leaves me wondering, why does the frame-rate recover when the object occupies less physical screen space? If the problem is geometry, then how could the size be a factor? It's not like I'm pushing less vertices, it's just that the fragment shader has less to do, but with the above simplifications - it shouldn't be doing much anyway.
If it helps, this is all running under OSX..
Incidentally, has anyone found the OpenGL Driver Monitor on OSX to be pretty well broken on Sierra?