Nautilus waits until it matches a file with the thumbnail to show it at all
To reproduce: Click on a directory with many thumnailable files, which have had thumbnails generated already (such as your photo album). Wait for a while.
What happens: Nautilus waits until it matches a file with the thumbnail to show it at all.
What perhaps should happen: Nautilus should show all files and then slowly load up their thumbnails as it matches files to thumbnails.
Why this is a problem: This makes loading files slower than it could be.
This is from an old Ubuntu bug that I think still applies.