Any recommendations on what to do with Photos.app's Library (and my iPhoto Library) if I want to format and clean install my very sluggish 10.10 installation? With older OSes you could just copy the iPhoto Library to your external and/or use a TC backup - but now I have two libraries with hard links (apparently the photos are still in iPhoto Library). What am I to do if I want to format? Google brings up conflicting recommendations. Any advice is appreciated!