DPM 2010 Backup using child partition snapshot takes too long

Hi All,

I have a trouble with backing up our VMs. Let me introduce you. DPM 2010 is VM (8GB RAM, 20GB page file, 4xCPU, 1Gbps LAN) running on Hyper-v2. It is backing up VMs from Hyper-v1. There are 13 of them and VHDs are together around 1,4TB. Protection group is configure to create express full backup every night and it takes for about 20hours. Backups are stored on RAID5 NAS which is connected to DPM as iSCSI target and it is equiped also with 1Gbps LAN.  

Is there any way how to increase speed of backup creation, because 20hours is realy too long.

Thanks a lot!