After recently upgrading to OS X 10.12, I noticed some SMB file transfers were taking a lot longer than usual. Instead of the normal 100MB/sec transfer speeds I typically see between my Mac Mini and my Synology NAS on a gigabit (wired) network, I was seeing something closer to 30MB/sec.
Turns out I’m not the only one with this issue. Searching Google for “10.12 slow smb” returns pages full of results of people reporting the same issue. Most of them say “switch to AFP and the problem goes away.” That’s nice but I specifically use SMB because I have a share that’s accessed by Linux, Mac, and Windows – and so SMB is the right solution to keep file naming consistent.
The issue seems to come down to Apple’s SMB forcing default enabling of “client signing” which ruins performance. Continue reading