Upgraded to 1.5.9 and same behavior: fast with vmd on and slow with vmd off.
I don’t know if this helps but, after some testing, writing speed looks good and the slowlyness seems to occur only when copying from server, but testing network the bandwith looks good too.
One thing that pictures don’t show is that, with vmd off, rsync freezes for a while (even a few minutes) before starting or at the beginning of the copy but not with vmd on. I tried to copy with scp and it hangs too. Locally rsync, cp or dd from /dev/zero work well.