Did you ever find a solution to this? We have the same issue on R2 CU3.
Deploying Visual Studio 2015 (6000 files, 16 GB) on 30 computers is taking days for the clients to download. Resource Monitor on the client shows ~1 MB/s from the DP that is on the same LAN with a gigabit connection. Copying the same files with SMB takes a matter of minutes.