One other thing going on:
Before, the download time for a picture was about 1.20 s for my ASI1600 on the USB 3 port. (On the USB 2 port strangely it was 1.08 s.)
After started to store the images locally, the download time for the initial images started with showing around 200.0 s (while it was about 0.2 s).
Next, download times increased with every image. I'm now at about 200 images in and download time is about 1.32 s, while it displays 1320.0 s.