I haven't seen "my" answer to this problem so I am posting both Q & A here.

I am doing initial WiFi backup of 265GB on a 16" MacBook Pro, running system 10.15.1, to a 2TB Time Capsule. I have done full backups many times before: they have been slow, but not like this. Today's backup includes long stretches of no network activity, punctuated by brief – but small — bursts.

enter image description here

The progress bar declines to offer a prediction, but my estimate is about a week.

I have rebooted, erased the Time Capsule (via AirPort Utility, not Disk Utility) twice and re-started. Apps like Music and Photos were closed anyway. Tried the throttle hack (https://www.imore.com/how-speed-your-time-machine-backups). Pored through dozens of outdated suggestions online.

What finally got it rolling? Answer to follow.


After about six hours of waiting for Godot, I tried this experiment: put the Mac to sleep (power not connected) and see if (still sloooow) backup proceeds while sleeping. It did not. (I let it sleep for a half hour, so the presence or absence of progress would be more apparent.) But... on re-awakening, the backup was more than 10x faster.

screenshot of network activity

Also, I found that when power is connected, backup does continue while sleeping. (PowerNap feature, checkbox in System Preferences > Energy Saver panel.) So while both laptop and I were asleep, 90% of the backup completed.

Solution? I don't know how general it is, and this is post-hoc reasoning, but my suggestion is: try putting your Mac to sleep for a while, with power disconnected. On awakening, it might just be 10x faster.

  • 1
    When you mac is not idle, TM tends to be slow. See gist.github.com/mayankk2308/00cc5be0bb8b150e3d7a149a3387c1d4.
    – amdyes
    Dec 16 '19 at 8:46
  • Another technique is to exclude many things for the first backup, and add them back later.
    – amdyes
    Dec 16 '19 at 8:47
  • Yes I agree with both points. And yet... the same trick just worked again for me. After migrating my Photos and Music libraries (I still use hard-copies!) the subsequent backup was large and slow -- pauses of several minutes between small bursts. Packets out/sec less than 1000. Go to sleep and wake up: packets out/sec >40,000. Dec 16 '19 at 22:00

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .