Taken from http://austintovey.blogspot.com/2012/04/optimal-iscsi-nic-settings.html
Optimal iSCSI NIC settings
This can help eliminate TCP retransmits between EQL and the host.Find the 2x iSCSI NICs in the registry, only change this for NICs connecting to iSCSI storage.
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces
Create two new DWORDS
TcpAckFrequency = 1
TcpDelAckTicks = 0
Restart the server.