Copying NAS to NAS using windows 10 shares

[bootit]

I have a NAS Thecus 5500 http://www.thecus.com/product.php?PROD_ID=22 with a JBOD 4TB drive EXT4 which I am copying through windows 10 Workstation i7 16GB to a NAS Thecus 6850 http://www.thecus.com/product.php?PROD_ID=71 with 6 x 4TB RAID 5 btrfs. It is through a 1000 ethernet connection. The files are iTunes device backups which are lots of small files. The copy begins fast due to cache at about 50 MB/s then it slows to 500 kb/s. I know there are other copying methods and I know small files slow the process. However is there something about btrfs or maybe something else that slows it down so much in this case? Thanks

 

[USAFRet]

This is pretty much 100% due to the tiny files and going through the network, and due to Windows being in the middle.

All 3 systems are doing thousands of conversations in both directions, at the same time.

Attached to my NAS, I have a few USB connected drives.
Copying large amounts of data from the NAS volume to one of the attached drives, doing it internally in the NAS, goes a lot faster than if I had my PC in the middle negotiating the transfer.