This video measures the frame rate of Metal Gear Solid Delta: Snake Eater running in Performance Mode on the PlayStation 5 Pro.
To measure, the FPS counter of the LG B4 television is used. So it will only show the frame rate if it is somewhere between 48 FPS and 60 FPS.
If the frame rate drops below 48 FPS, then the counter will show 60 FPS. Thus, if the counter shows 60 FPS but the video appears choppier than usual, then it indicates the frame rate has dropped below 48 FPS.
You can find the video below:
As you can probably see, the frame rate regular drops below 48 FPS in the stress test, even in Performance Mode.