What is the expected performance of a single rotating OpenGL-Triangle
I am hunting a performance problem in my own OpenGL-based application and noticed that I got less than 10 FPS even without drawing anything. Just out of curiosity, I tried the OpenGL Window Example that comes with Qt to see what was the expected performance. This example shows a single rotating triangle, so every GPU of the last 10 years should be able to handle this load.
I use a Core i7-6700 with an NVidia Quadro K620 running Windows 10 Fall Creators Update and Qt 5.9. When launching the application, the windows has a size of about 510 by 380 px and the animation of the rotating triangle is smooth. The windows task manager reports a GPU usage of about 2.5%. When maximizing the window on my 2560x1440 screen, I get barely 10 FPS anymore and the GPU usage goes up to 100%. I know that the Quadro K620 is not a very powerfull card but I was expecting that it would be able to fill my screen with a stable 30 FPS.
Now I am wondering whether my computer is configured in a completely weired way or whether this is the expected perfomance on a system of that class.
I tried two additional computers:
A Surface Book runnning a i5-6300U using both the integrated intel graphics and the dedicated nvidia graphics, similar to a GTX 950M. The integrated intel provided a stable 30 FPS, but went up to 83% usage. Using the integrated graphics card, the results was also a stable 30 FPS, but I expect the provided usage percent of also 83% was for the internal graphics copying the data from the nvidia-card to the display memore. Note that the Surface has an even higher screen resolution of 3000x2000 px.
A thinkpad W520 with a Core i7 3720 and a Quadro K2000m
Both the integrated and the dedicated GPU provide a stable 30 FPS, using the dedicated GPU shows a usage of 13.5% but on only a full hd screen of 1920x1080
Question 1: What performance do you get when running the OpenGL Window Example Fullscreen and what is the GPU usage?
Question 2: Am I doing something fundamentaly wrong here? Maybe my Quadro switches to shared memory at my high screen resolution because it only has 2 GB of RAM?
I would try some openGL test program and see what it gets.