On servers running Windows Server 2012 with Broadcom Network adapters file access performance (read and write) within and between VM’s on Hyper-V are reported to be terrible by some administrators.
I’ve had this problem myself with my Dell servers runnin Broadcom network adapters and after a few hours I found a solution that actualy solves this problem.
disable ALL instances of TCP Offloading, and Recieve Side Scaling on the HOST’s LAN NIC and disable the Virtual Machine Queues property . These options are found here:
Device Manager tool, expand the “Network adapters” section, right-click on the adapter that supports the VMQ feature, and select “Properties.” In the properties window, select the Virtual Machine Queues property, set the value to Disabled”
More info can be found here: