Job rate on backup.

I just replaced our tape library from a Dell Powervault "older model" to a Dell TL-2000.

I did a 4 GB backup job to get a feel for the speed of the job rate. The job rate came in at about 450Mb/min.

We have had other jobs come in a 1.6GB/min.

Question

"What" and "where" can i look  to make sure I am configured with "proper settings" and/or "latest 'req'd stuff'" to maximize my job rate?