Backup and restore times

It depends. If the file server contains millions of small files, then backup & restore times will be slow and this is to be expected.

It also depends on the storage subsystem of your file server and the number of IOPS it can handle.

I thought the network would have more of a impact on the speeds.  thoughts?

For 15MB/s network speed you got good results. Imho the bottle neck here is your network. See with this calculator how many MBs are transferred per second or minute: http://www.ibeast.com/content/tools/band-calc.asp

So if I use a Approx in this next example it means that my 15.68GB that took 18mins is well above 45Mbs and just below OC3 156Mbs.  and your saying that's normal or not normal?  Gigabit switchs and Cat5e

Why does everybody automatically assume the network is the bottleneck, when this is rarely the case in network backups?

Gigabit ethernet = 100MB/s.  
The restore throughput was only 15MB/s, using only 15% of available bandwidth.

Most file backups require IOPS, not throughput.  Are you backing up large amounts of small files?  What is the storage subsystem of your file server?

I did a search for the Barracuda 390 and found this is a low end backup solution. A review claimed speeds between 9MB/s and 23MB/s for an average file system backup.

So you're getting what can be expected and the bottleneck is in the Barracuda.

@robocat Do you have a link to your findings?

http://www.pcpro.co.uk/reviews/servers/386974/barracuda-backup-server-390

"Performance for the 390 is similar to the Unitrends Recovery-312. A 23GB folder copy averaged 21MB/sec, while a Windows 8 full system backup ran at a more lowly 9MB/sec. "

I disagree with "I did a search for the Barracuda 390 and found this is a low end backup solution. A review claimed speeds between 9MB/s and 23MB/s for an average file system backup.  So you're getting what can be expected and the bottleneck is in the Barracuda." - I've tested in production and gotten a network assessment done.  Our network switch was causing performce issues.

As I said in my comment ID: 40715800

Are all switches really working on Gbit speeds?
If yes then you have to contact Barracuda directly and request explaining.