Slow backups on macOS

I’d like to add my own observations (to what others have reported in older threads) that Duplicati on macOS is very slow (compared to Windows). I’ve run it on macOS High Sierra for over a year, and now switched to a new 2018 MacBook Air running Mojave. In both cases, during what I presume is the initial ‘compare’ stage when the backup is starting, it takes easily 30 to 60 minutes before the actual data upload starts, and during this time, the laptop runs hot and the fan goes into overdrive. This results in daily backup times that range anywhere from 45 minutes to 1.5 hours. In comparison, on my Windows 10 laptop, this is done in under ten minutes (total).

I am using client version (which is the advertised stable build on the Duplicati homepage) with Mono Mojave 10.14.5, 16GB RAM, 512GB storage (half of that used). I am uploading to NextCloud via WebDAV. AES-256, remote volume size is set to 100MB, with backup retention set to delete backups that are older than 12 months.

Any help or suggestions are appreciated.


P.S: Source size is ~190GB, backup size is ~280GB (227 versions)

I am just browsing through the release notes of the canary builds and came across this one.

In the notes, it says “Fixed CPU/memory issue on MacOS”. I’m assuming this is what I am experiencing.

Update: Nope! Updating to the latest canary build (, from May 12) unfortunately didn’t change anything. It stays at “Starting backup” for 30 minutes (or longer), accompanied by lots of heat & loud fans.

I am experiencing the same thing. When trying to do a 1TB backup, I could never get there, so I broke my backup into 5 pieces. This allowed each job to complete, but I still get lots of heat and fans when each job runs.

Thanks Mark. I guess there’s no love here for macOS. Anyone? Anyone? Bueller? Bueller? :slight_smile:

Just bumping this topic back to the top. Any other macOS users here who have found a solution to this problem?