iPhone backup takes too long I am an Apple User since 1983. But I do not know whey my iPhone Backup (with Encryption on) takes 23 to 26 hours!! I am puzzled. (I have iPhone 6, 10.1.1 iOS, Mac OS X Yosemite, iTunes v.12.5.3, MBP late 2008.) Any answers? Thanks!
How old is your Mac computer (and its internal hard disk)? I ask because hard disks are known to fail over time, so if your hard disk is over 3 years old, it could be that your disk is failing and therefore writing information to the disk could take a really long time.

Fortunately, replacing a hard disk is actually quite easy/straightforward.