BE2012 Convert to VM "VERY VERY SLOW" What CAUSE it???

I m using vmware with BE2012 local store.

I have setup clone my BE server itself after backup and convert to vm in a  remote VM store ..on intranet BUT it is very very slow 100M/min.

( sometimes i exp access right / file log issue...ignore these first)

Any idea ...if i clone( convert)  to lcoal it is ok fast  ...but if i clone the the remote nfs store/ iscsi ...it is very slow.100M./min.

Direct copy from peer to peer is quite fast as intranet 100m/s