Sharepoint GRT data index catalog job very very slow

Hi everybody, we report the following problem: the meta-index catalog job, that starts after the backup job of sharepoint server with GRT enabled, run/is very very slowly (less than 5 MB/s) so it is not able to end correctly (we stopped it after 2 days running).

The backup server is BackupExec 2012 SP1 installed on Windows 2008 R2, the backup job of sharepoint run on deduplication storage that stands on local.

Any idea?

Thanks for your help.