Delay archiving in Backup Exec 2012

I have a question.

 

I set up an archive job to run in a volume of 10TB. As I had problem of execution, just dividing this volume. I made a backup of 1.5TB and gotten, started the archiving. The Archive and Backup is performed in the same storage. Backup is done with the Deduplication option. Job's average rate of 2.5 MB / min.

 

My doubt is that the archiving Job took one day to start. In the meantime, I believe that has been in process inventory backed up and then start the archive process. Now the job of archiving rate is below 1 GB / min (slow).

 

Is right or what can be done to improve?