Getting short on space, and looking for where 1.4GB of disk space in my home folder was being used, I find..
~/.cache/thumbnails/normal - more than 66000 of them!
OK - so delete them, but does the space ever get cleaned up to be contiguous ever again?
I am not expert at fragmentation, but I don't think it is something that has gone away, and my instinct is telling me that this cannot be good. Even if there was a scheme that kept the number limited to a reasonable stash of the most recently used, the joy of thumbnail previews has this price in small file creation.