LRcatalog taking about an hour to backup.

I am using a PC with Windows.  I didn't update LRclassic recently as I've heard there are many problems with this update.  However, about a week ago, each time I backup my catalog, it takes a full hour for LR to complete this task.  It used to be about 10 minutes.  Any idea why it changed so abruptly and what I can do to change this?  Thank you!