Low FPS

Hi,
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?

Thanks
Navid

It’s the lighting in the room. The camera will lower the FPS to improve exposure when there’s little lighting.