[Milhouse]

What about pre-caching of my private picture collection? Is this supported? In my case the previews are still created on-the-fly, which puts too much load on my rpi.

Am I doing something wrong? How can I pre-cache my pictures library too?

Picture folder thumbnails (the little composite folder images) are created by the GUI as you browse your picture library and can't currently be pre-loaded by JSON, however such thumbnails, once cached, will be retained by default when pruning (controlled by @prune.retain.previews).

The pictures themselves will not be preloaded into the cache, for several reasons: 1) I didn't have much success caching pictures via JSON; 2) I'm not sure it would be a good idea to have your entire picture library reproduced in your cache, and 3) the standard slideshow facility doesn't appear to use the cache as it doesn't store in the cache the pictures it shows, suggesting the cache is being by passed which is understandable and reasonable. However some addons do dump your pictures in the cache, which is probably not (IMHO) a good thing (think: cache bloat). When pruning the cache, any pictures found in the cache will be deleted by default unless you enable @prune.retain.pictures.