Firstly, my backups to an external USB 3.0 drive are now extremely slow on my MBPr Late 2013. I've recently upgraded to Sierra GM to see if this solved the issue, but it hasn't. Secondly, backups to my AirPort ac Time Capsule don't seem to get anywhere - I left it overnight on preparing backup and it was the same over 12 hours later. Looking in the console log, there's a lot of entries for the following: "AFP_VFS afpfs_vnop_ioctl:afpfs_FindForkRef failed -1". Has anyone got any ideas what I can do to at least speed up the backups to my external drive? It used to zip along at a decent speed, but it took over 24 hours to complete the most recent backup of 300GB. I've also used the sudo command to stop the throttling of the Time Machine process, but the Time Capsule still gets stuck on Preparing Backup... with Activity Monitor showing high CPU usage but no network activity indicating read/write on the network drive.