I test the usage and the temperature of the CPU and the GPU. And I also check, how much memory the game uses.
You can also see how much FPS the game runs with, and you see the VRAM Usage too.
System: Lenovo ThinkCentre M91p
Processor: INTEL Core i5-2500 3.30GHz
System Memory: 10GB DDR3 1333MHz
Video Card: PNY Quadro P1000 4GB GDDR5
Unfortunately I can't set the Texture Pool Size to more than Medium because it requieres more VRam.