Moving VM's between cluster is slow

Hi,

What is the average time you would expect a VM to move from one host to another using live migration? We are seeing times of between 20-40 seconds.  So if we have about 60 VM's it is taking a long time to put a host into maintenance mode as Hyper-V does one at a time.

What speeds to you see?

We are using Cisco UCS Blades in a Flexpod so would expect it to be fairly quick!