AD Domain Controller System State backup performance

I was just curious if anyone has experienced this.  We're migrating from CommVault where our DC File System backups and System State take all of an hour or so.  In Avamar the System State alone takes 4+ hours to run, one DC went 7 hours last night?  Any ideas on what causes that. 

We have four DCs (average runtime for each is 4, 5, 4, 7 hours).  The schedule are all staggered so they're not kicking off at the same times, though with the long runtime they overlap one another which is kind of unavoidable with the backup window.  Was wondering if I've flipped an option maybe that's causing something weird to happen causing long run times or if this is normal behavior in Avamar?

The backups finish successfully which is good, but our Windows team is doing some AD work and wanted to do a backup before they started and, being familiar with CV, they figured the backup would be an hour and then they could get to work, until I told them they'd have to wait four+ hours, they're not really liking that so much, so much so they're pushing mgmt to keep CV around for things like AD, Exchange, SQL,and SharePoint,  And I won't mention the comments the Win guys gave me about the Avamar GUI.