The Test_img.py script only does the calculations on two images once.  It also measures the time it takes to transfer the images from CPU -> GPU -> CPU. Since there is so little data, the time measured might be dominated by this transferring time and not the actual model computations. You might actually run the script faster on the CPU.
What is the goal if you don’t mind me asking? To run this script as fast as possible? Train or run with webcam? Verify that your 2080 is faster than 1080?