I don’t understand why you wrote that there are 2 screens. There is only one screen and it is widescreen.
On a larger screen, the project works without problems and the GPU is not overloaded.
The scene is very simple, I have given a screenshot above, the problem is clearly not in the scene. Even if there were twice as many objects in the scene due to the wide screen, performance would not drop dramatically by 10 times with minimal graphics settings.
The original message also states that when the resolution of the render is reduced to 80%, there is no problem, but when the resolution of the render is increased to more than 80%, the problem occurs. That is, there is a sharp edge on which the problem consistently manifests itself with the same number of the same objects on the screen.