I let the photos App idle for a complete whole day and just finish scanning 9,000 photos, while I have 100,000 photos in my library. Still have 90% of my photo to go. That means I have to wait 10 more days to complete this new face scan. Is it really take such long time for face scan? Meanwhile, the Time Machine keep "Preparing Backup" forever..... Any one has idea on this? Thanks.