Are you talking about the "Select Missing Images" feature?
It is indeed slow on large catalogs such as yours. It was never intended to perform well with a contact sheet containing hundreds of thousands of images. It's done via getting all of the images from the catalog resolved as local images and those that fail are "missing" and are selected.
If you can think of way to make it take seconds, I'm all ears.
-Kirk
Yes, I am. I am not a programmer, and do not know the art of the possible (or impossible).
If you carry out a Full Sync, that counts the missing files. Then, if you select Find ¦ Select Missing for the same entire catalogue, it takes ages to go through the catalogue again to extract (in non-programming terms) the same data. Would it not be possible somehow to retain that data from the Full Sync which identifies the missing files, and couple this with an option for the immediate removal of those missing files, without having to search all through the metadata and make a new selection all over again? That would not speed up the Full Sync, but it would make a huge difference to the speed of removal of the missing items from the catalogue, assuming the user is happy to remove the files without further review (which I would be): maybe only a matter of seconds
Maybe it is not technically possible, but otherwise all a Full Sync is doing (in relation to missing files) is telling you how many missing files there are, not providing a solution for removing them from the catalogue, which may be interesting but it is not particularly useful for the management of the catalogue.
I await being told that this cannot work!
Graham