Windows 2012 (including R2) Hosts will by default issue SCSI "TRIM and Unmap" commands equivalent to the entire size of the Virtual Disk. This behaviour is regardless if the 'Perform a quick format' option is checked. This will significantly slow down the format process.
A ticket for HostPowerTools was also created to allow a workaround for this : Disable TRIM/UNMAP before formatting a volume, and re-enable it right after.
It is possible to disable the SCSI TRIM and Unmap feature on the Host for the duration of the format.
Using a Windows CMD window on the Host issue the command:
To re-enable the feature use the following command:
To verify the current setting use the following command:
Information about this new feature can be found here.