Slow Speed with Acronis Backup for Windows Server on virtual machine

Hi,

I use Acronis Backup and recovery for windows server in th epast with a physical server. When I migrate this to a new virtual server on VMware I get a bad network performance. Max. 3,4% network is used so the backup need 22 houres. I download a new 11.5 testversion, but the traffic was the same.
I checked a copy with a "big" file to the nas and the network traffic grows up to more than 50%. The server has a gigabit network interfaces and the nas too.

What could be the problem?

Holger