Images loading very slowly when browsing a network directory
When opening a samba share from nautilus and opening a picture from a directory with images, the image loaded opens quickly. Using the thumbnail pane to select a different picture, however, is very slow. The selected image takes forever to load.
One plausible explanation is that the jobs that are taking care of thumbnailing the images visible in the pane have higher (or the same) priority than then one that has to load the image selected. So the image won't be loaded until after the thumbnailing is done.
Once all images have cached thumbnails, however, the problem persists, although now images load a bit faster, but they still take considerably more time than if one loads them from Nautilus. Observing the network usage from gnome-system-monitor shows that there's a lot of incoming network activity, but considerably more data is received what one would expect from the size of the picture.
Further observing network activity led me to notice that just hovering over other images is enough for network activity to spike. I suspect that eog is loading the entire image in order to get the image information that is displayed in the tooltip. If you quickly move the mouse over the thumbnail pane, so that you go over all the pictures, it's clear that eog is loading every image for no reason, as once you hover away from a thumbnail, you don't need the tooltip information anymore.
I assume that this always happens, but when images are local, in a reasonably fast computer this is not noticeable. However it's clear that there's a lot that could be improved here using task cancellation and prioritization.