Mmm, okay, you can probably increase the resolution more.
First, find what the camera max fps is without recording for the format. That will give you an idea of what the upper limit is. Note that the FPS will drop once you have to go into single buffer mode from double/triple buffering.
Then, the SD card itself will force erase times on you. This can hurt the FPS also, to get pst this you want to turn the image fifo on.
Do: sensor.set_framebuffers(n)
Where n is a value greater than or equal to 4. Once you do this the camera system will store images into a fifo in ram. As long you are writing data out of the fifo quick enough you will get the max frame rate. You need to do this to overcome random periods where the SD card blocks you while it’s erasing. Sensor.snapshot() is the call that removes an image from the fifo.
200x200 is 40000 bytes per image, so, you should be able to have a lot of these in RAM. That said, note that SD cards transfer data faster the larger the block size. So, weirdly enough… you probably won’t see any speed impact moving data to the SD card even if the image size increases because it’s all done in on transfer at 200mbs. I.e, the only way to get the highest bandwidth to an SD card is to do giant transfers. When the image size is smaller the SD card actually gets less efficient.