Drag and drop using Windows Explorer.How are you doing the transfer?
Do you mind elaborating? I did the same exact copy and paste from one FreeNAS box to the other and it was blazing fast and problem free. The reason I asked is because I wanted to know. "There's your problem" tells me nothing.There's your problem.
zfs snapshot srcpool/datasetname@20170624 && zfs send srcpool/datasetname@20170624 destpool/datasetname && zfs remove srcpool/datasetname@20170624