When I run Duplicacy on my machine (with no other significant programs running) I get the following network traffic pattern:
From that graphic I assume, Duplicacy does open a file, encrypt it and then sends it over the network and again.
I think the network and CPU could be used more effective if that would be separated in two threads, so the network and CPU are steadily used to their full capacity. (or configured limits)
Especially with large backups, this could speedup the whole process quite a bit as most of the time the network is the bottle neck.
Looking forward to get your thoughts on that, or if it maybe is a configuration error on my side.