I recently bought a H7 board with OV7725 sensor. When I run the helloworld.py I get the maximum of 37 FPS. I have tried different examples with smaller frames sizes in Gray scale. however the maximum fps remains 37. The firmware version is 3.6.8, I am running it on a windows PC and I am not using SD card on the board. Sometimes the FPS starts around 18 and rises to 37 in a few minutes. Could you please advise what the problem might be?