Certain modern switch hardware such as HP Procurve switches can have issues transferring multicast packets between VLAN's.
The Ghost transfer is significantly slower than would be expected for a high speed switch.
This issue is due to an incomplete or incorrect configuration of the multicast options on the switch itself.
Modern layer 3 switches require PIM to be enabled for each VLAN. This facilitates the routing of multicast packets between VLAN's. Ideally this should be PIM_SM (Sparse Mode), It may also work with PIM-DM and Dense-Sparse, though those protocols are not supported for use with Ghost.
Try turning off Flow Control and see if that increases the cloning speed as it will disable Pause Frames. Flow Control is a parameter that allows the user to enable or disable the receipt or transmission of PAUSE frames. PAUSE frames enable the adapter and the switch to control the transmit rate. The side that is receiving the PAUSE frame temporarily stops transmitting. Flow Control can be modified on the NIC.