Hyper-V 2012 VHDX issue

We have a VM which was recently created to host an Exchange 2010 server.  We already had another VM on the Host that is hosting an AD Server.

When the new Exchange VM was created we used the VHDX that was preinstalled by Dell for the 2012 OS.  I believe that VHDX that should have been used tocreate a new VM actually became the new VM.

The performance on that VM is poor and when you INSPECT it from the Hyper-V manager it is type "Differencing virtual hard disk" while my AD (which is performing well) shows as "Dynamically expanding virtual hard disk"

What would be the best way to take this production hard drive and move it to a new VHDX?  Would this be why the VM is running poorly?

Very new to Hyper-V and '12.

Thanks,

Dan