For a long time I've been using rsync and a usb cable to get the photos from my phone's SD card onto the PC. This is the current command:
rsync -azvu --ignore-existing --progress SD-Karte/DCIM/Camera/ /home/cardamom/Pictures/PhonePictures/
It took me a while to get it right by trial and error and reading the docs. There are probably many thousand of photos in each directory but one would not think that it would take a computer that long to compare two lists a thousand long and if there is anything in the source which is not in the destination, bring it accross.
Yet, if I take a single extra photo with the phone, or even no extra photo, it will sit there for what feels like two or three minutes thinking and then transfer the one photo in about a second.
Am not sure if the bottleneck is in the rsync command which is doing something I don't need like comparing hashes of file, or if it is in the SD card of the old smartphone, which somehow has some big inefficiency.
Is there anything inefficient in the rsync command, or otherwise some kind of measure to make it go quicker inside the phone?