I haven’t personally done benchmarks, but I thought I read that using the SSH protocol with rsync was a lot slower than using the rsync protocol due to no encryption overhead. Did you see differently?
Yeah, I can definitely believe that SSH can become the bottleneck, or pose a significant overhead, in many setups. But, in my tests, using unencrypted rsync daemon mode was even slower for some reason!
I ran some tests with my network storage PC, downloading a 50GB zero file from my workstation (both connected via a 10 Gbit/s link):
curl -v -o /dev/null
ssh midna.lan cat > /dev/null
But, once you write to disk, throughput drops even further:
As you have a really fast network, I’m wondering if compression is to blame? IIRC, in both programs compression is disabled by default, but distributions might change it.