I just upgraded to Lightroom 6. I updated all 3 of my catalogs. Two of them have little in them and seemed to be OK. The third one, I have 25,000 photos in it and when I go to that catalogHard Drive over working, I can hear my hard drive working away and it won't stop. Is Lightroom doing something here and it's taking awhile? I'm not sure why Lightroom is making my hard drive work so much. Can anybody explain what is going on here? The other two catalogs don't cause my hard drive to work but have less than 2000 images in them each.
One possibility is that it is performing the facial recognition in LR 6. You might want to see if turning that off fixes the problem.
Awesome, that was it it seems. I'll come back if the problem occurs again but I think my problem is solved.