Hi,

When using a buffer with about 5000 images,
image-dired-mouse-toggle-mark takes about 1-2 seconds for one image.

This is not a big problem. But when using this function on a region with
about 200 images, then you need to wait several minutes for completion.

That's because image-dired-thumb-update-marks is called in the macro
image-dired--on-file-in-dired-buffer and therefore unnecessarily for
each image in the region.

What could be a good way to avoid the repeated calls to
image-dired-thumb-update-marks please?

TIA for any help,
-- 
           Peter