Duplicati not using full network speed


I am using Duplicati on Ubuntu 16.04 to backup to a Synology NAS. The connection is 1 Gbit Ethernet cable.
I have set “Upload volume size” to 200 MByte.

During backup, I have the following observations:

  1. Duplicati only seems to use only one of the four CPUs in my computer.
  2. The network is only being used maybe 50% of the time, sometimes even much less. That means I see maybe 20 seconds of data transfer, then a pause of at least 20 seconds with no or very little data transfer.
  3. I am seeing a maximum of 100 Mbit/s being used. During, the 20 second data bursts, this speed is very stable.

My overall concern is, that the backup process with Duplicati should be much faster then it is right now.

Observation 1) might be an overall issue. Is this a decision by design?

Observation 2) might be a result of 1) - why is the network not being used fully?

When I am doing file transfers between my computer and the NAS, I am seeing typical speeds of 500 to 600 Mbit/s. Why is the maximum speed during backups with Duplicati exactly 100 Mbit/s? Why am I not seeing higher speeds?

I would be happy if others could share their experience and thoughts.

Best regards,



It sounds CPU bottlenecked. It can be helped by lowering compression standards, but you’re likely more interested in this part:

Multi threaded processing was implemented in the beginning of the year, but the current beta does not have multi threading. Lots of testing and bug fixes have been done to bring it into a stability.

The next beta will have it. It should be out soonish, but there isn’t a date on it right now.