Time Machine Slow? Speed it up With This Terminal Hack!

Time machine slow for you? Speed up the initial backup with the following command and run it in a terminal window. To open up terminal just search for it using spotlight and start it.

The terminal window should look something like this:

time machine slow

Speed up time machine backup terminal command:

sudo sysctl debug.lowpri\_throttle_enabled=0

  • If the backup is currently in process when you are typing these commands, make sure to restart the backup and you should see a time machine backup speed improvement.

Return to default when done (a reboot also returns the settings to default):

sudo sysctl debug.lowpri\_throttle_enabled=1

When you enter the commands above you will be asked for your password. It is the same password you use when logging in to your Mac or installing new applications. It won’t show the password when you are typing it.

Also scroll down to read the comments for this post. There are some nice tips from the readers of this site as well!

Time Machine Slow Due to Low Priority Settings

The reason for time machines initial backup being slow is that it defaults to a low priority mode. When you enter the command above it will increase the priority with the cost of using up more resources from your Mac. The benefit here is that the initial backup will go much faster, and I would certainly welcome that over some more power savings.

When you are done, just remember to return to the default mode, if not your machine may feel slow because not only time machine but other background tasks are affected by this command as well.

When the initial backup is done it should be no big issues with the backups after that. In most cases it is the initial backup that makes time machine run slow. Most people just leave it on overnight and it takes care of itself, but if you are in a hurry the suggestions in this article should help.

Related content

Other Suggestions if Backups are taking a long time

Are you backing up via WiFi? That can slow down backups. Make sure you are close to your access point / router or use a physical network cable to connect your Mac directly to the router. Make sure you are connected to a fast 5ghz network.

Format or check the hard drive you are backing up to. Open up disk utility and run a check on your hard drive. Maybe the drive is getting bad, or a repartition and a reformat could help.

If you have cancelled or unexpectedly interrupted the previous backup time machine may take a longer time when making a new backup again.

If you are running antivirus try disabling it during the backup as it may slow it down.

Virtualization apps like Vmware Fusion or Parallels can often write data to your hard drive and this may keep time machine going all the time. Consider excluding virtual machines from your backup.

50 thoughts on “Time Machine Slow? Speed it up With This Terminal Hack!”

  1. This fix was AMAZING! I have a new, 2018 MacBook Pro with 2.6GHz, 6 core processor. The Macbook is directly attached to a LaCie 4big Quadra. Before this fix, it was sooooooo slow to have Time Machine back anything up. I often found myself killing the backup job so I could grab my Macbook and head off to a meeting. What use to take hours, now takes minutes! Thank you so very much for sharing this!

    Reply
  2. Grrrreat, thanks! Kicked the process from twelve to less than two hours. Is this a solution you can use for, for instance, any update process? Keep up the good work, kind regards from The Netherlands. I’ll share this post in the Apple Netherlands/Belgium support group on Facebook.

    Reply
    • Leon: Glad it worked! It may be possible to use this command for other background services as well. For example updating icloud photo libraries? I am just guessing here tho. Thank you for sharing the site, it helps. 🙂

      Reply
  3. hey, thanks for the advice. My throttle setting did go down to 0 from 1 after entering the command, but the backup didn’t get any faster, even though I’m using a brand new Samsung T5 SSD, connected via USB to my Macbook 12″ 2016. Do you have any more advice for me? Thanks!

    Reply
  4. Did nothing for me where as the original sudo sysctl debug.lowpri_throttle_enabled=0 made back go from 400 kb/sec to 40 MB/sec.

    And that makes sense: if the back up is obeying some throttle flag then changing the priority makes no difference.

    Reply
  5. I get the same speed out of Time Machine whether I backup to my NAS over Wifi or try to backpu to my external LaCie hard drive. That’s just not right.

    Reply
  6. what is kind of dumb is Apple could just have a toggle switch on the Time Machine interface to enable or disable this throttle setting (and could revert to off when done).

    Personally, I do first backups when I am not going to be using my computer (eg overnight). Its the perfect time for the throttle. it could even default to this setting for the first time.

    Context: I recently bought a 1 TB SSD to replace my now-useless 2TB time capsule. It had been doing a first backup of 400GB and was on hour 40 and only at about 90%. I googled and found this thread and its cruising along now..

    Reply
  7. Do you have to restart computer or type in a command into terminal to shut this setting off after your backup is complete?!

    Reply
  8. Even after running command line in terminal, I was having same issue as Raphael granite. I then restarted the backup as suggested by bjokib. That made all the difference in the world. Backup went from 16 hrs to about 10 minutes!!!

    Thank you bjokib and All About Apple.

    Reply
  9. No, I tried that, but I found this and it worked.

    sudo sysctl -w debug.lowpri_throttle_enabled=0

    Still seems to be SUPER slow, but I did get the enabled 1->0 response, so I guess it worked? After half an hour, I have backed up 171mb out of 655gb… Sigh.

    Reply
  10. I just don’t get it. This is not working for me. Have a new MacBook Air I got about 6 months ago. Bought a new WD Passport for Mac 4TB backup drive the other day to replace my old one that is nearly 8 years old (WD Passport for Mac 500GB). Original backup to the old WD went quickly6 months ago. Even with making the terminal command change recommended above, my backup with the new WD drive is at 500mb after nearly 10 minutes and estimated time to complete is a full day (for 250GB internal drive)!. Isn’t USB-C supposed to be faster transfer speed as well (old backup drive was USB 2.0)? Really annoying that the newer drive is actually slower.

    Reply
  11. Of course. I erased the previous partial one from the new drive and restarted from scratch.

    I can cut and paste a file directly and it takes about 30 seconds to transfer 1 GB. After 80 minutes backing up with Time Machine, even after using the throttle command above, it had transferred 9 GB. I just quit it.

    Reply
    • That sounds really strange… I have nothing else to suggest terminal wise. Maybe a SMC reset or PRAM reset could solve it. If you can copy the file manually in good speed its obviously nothing wrong with the hardware. 🤔

      Reply
  12. Well, I don’t know what SMC and PRAM are, and I generally don’t like messing with too many setting on things not knowing what they do. If I can take the drive back I may just do that. Really annoying that it is slower than an 8 year-old USB 2.0 drive from the same company. I was worried about the other getting too old (my previous comp died at about 8 so I figured it was time to upgrade the backup drive as well).

    Reply
  13. Hi,

    This is ridiculous… my big backup with Parallels disk images and so on takes forever… so I’ve changed this. But since I’m using time machine editor and not the dumb schedule in MacOS, so my backups running in the night, I want to make it permanent. Do you have any idea where is the sysctl.conf equivalent in MacOS?

    Thanks
    L:

    Reply
    • Not sure if you can do it permanently. Maybe you can add it to a startup script and add it under login-items on your account?

      Reply
  14. Thanks. It seems in my case it was not a solution because after changing this, my backup still stucks at 107 GB…. My suspect is some large vm image which never finishes… however I’m using Parallels which has some Time Machine optimization

    Reply
  15. The command doesn’t work for me either. I have a 2019 MacBook Air, and a new Seagate 2TB 3.0 USP drive. I cut and pasted the command instruction to the terminal during the initial back-up. Since it was still backing up slow, I then deleted the backup file from the Senate drive, rebooted my MacBook, went to the terminal and added the instruction, and then started a new initial Time Machine backup… which is now running painfully slow. At the current speed, it should take about 12-16 hours to back up 200 MB of data.

    Reply
    • Very strange, this command worked pretty good until recently. Maybe there are something in Catalina that prevents it working? I have to research that.

      Reply

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