VMware VM backup throughput, backup restore performance

Dear TSM fellows,

I am curious what throughput you can achieve when doing VM backup and restore of VMware virtual machines with the TSM BA client.
We expected much more and what we see is "incremental forever - full" backup with 80 MB/s over 10 GBit LAN (NBD) and 120 MB/s over 8 GBit SAN (SAN). Both source and target storage achieve at least 350 MB/s at sequential copy tests (using just normal Windows copy). VMCTL is on disk, backup data goes to file device class. Multisession VM backup achieves 80/120 MB/s per session, which shows that the LAN/SAN connection is not the bottleneck.

What is your experience with backup/restore performance of VMware VM´s?

our config is:
TSM server 6.3.4.300 on Windows 2008R2
TSM BA client 7.1.0.3
vSphere 5.1
backup proxy is the Windows TSM server

I´d appreciate if you would share your experiences.

Thank you and best regards,
bonobos