NAS vs VHD, Skip Pass Through Disks

Hi!

I have Seagate NAS storage device which is very slow and backup jobs taking a long time. Will the backup performance increase if i create a VHD from NAS to BE Server (Win 2008 R2) and then take the backup?

Secondly, is it possible to skip pass through disks while backing up Hyper-V virtual machines?

Thanks.