This is the initial backup that’s really slow unfortunately. I’ve left it overnight and it’s managed 500GB in 8 hours. These are video files it’s backing up, so there’s no reason for it to be so slow. Copying the files manually would take about 80 minutes at the most, so duplicati is at least 7x slower than a raw copy.
Looking at Process Explorer from Sysinternals and bringing up the stack trace on the thread generating the most CPU load, it seems the call to mscorlib.dll!System.Security.Cryptography.SHA256Managed.SHATransform is likely responsible. I plan to fire up visual studio and see if I can’t get some profiling happening.
Duplicati has lots of potential so it’s worth my time I think to delve into this one.