Rebuilding thumbnails

[cookp]

Hello
I have some backup files of my reunion family tree file saved without thumbnails in the cloud. On rare occasions, I wish to scrap some of the family tree research I am doing and go back in time to an earlier copy of my family tree.
The problem I have is when opening these backup reunion files (copied from cloud to local drive first), the program rebuilds thumbnails which takes some time, and I wondered, is there any way of opening a family tree file so it does not try to rebuild its thumbnails?
Paul
PS I am wondering whether I should simply save the backup files with thumbnails, although they take up more space within cloud storage.

[cookp]

I worked out why the thumbnail creation was taking so long which is on me. I decided to save some space on my local drive, so within the iCloud folder, I had selected "removed download" on many of my locally store image files (within various folders etc). So in creating thumbnails, the image files had to be re-downloaded from iCloud before being able to create a thumbnail which took so much time.