I am using a Raspberry pi 4 with a canon Ra, and transfer takes around 4 - 5 seconds on USB2 and 3 - 4 seconds on USB3, I am not saving the files on the camera SD card.

I store fits files on the sd card.

The raspberry pi is using s Sandisk ultray32Gb class 10 A1 micro sd card.

I did try running the raspberry pi entirely on an nvme disc using a USB adapter. In speed tests it is dramatically faster, and it speeded up boot and loading apps a bit, it made no difference once taking sequences of images.

I find the serial operation of ekos / indi really annoying, and it also means the camera heats up more, increasing the noise.

I have found that when the camera is not taking a picture it is heating up quite quickly, when taking long exposure photos it cools down while the shutter is open. On my camera the temperature is recorded in the raw and fits file.

Using libgphoto2 (which is what the indi dslr driver uses I believe), kit is quite easy to :

1. open shutter
2. close shutter
3. open shutter for next image
4. transfer image while next image being taken