DDBoost File-Replication - Why is it slow?

When using ddboost file-replication from one storage-unit to another on the same dd, why does it take such a long time? Why does it go over the network?

I see this:

ifgroup show connections

Group-name       Status    Port     Interface   Client Write   Client Read   Repl-out   Repl-in   Total

--------------   -------   -----   ------------   ------------   -----------   --------   -------   -----

none             disable   ethMa   10.0.95.86              0             0          0         0       0

InterfaceGroup   enabled   eth3a   10.0.95.87              0             0          6         6      12

InterfaceGroup   enabled   eth3b   10.0.95.88              0             0          6         6      12

InterfaceGroup   enabled   eth3c   10.0.95.89              0             0          7         7      14

InterfaceGroup   enabled   eth3d   10.0.95.90              0             0          7         7      14

--------------   -------   -----   ------------   ------------   -----------   --------   -------   -----

ddboost file-replication show performance

09/12 03:01:32

       Outbound                Inbound

Pre-comp    Network     Pre-comp    Network

  (KB/s)     (KB/s)       (KB/s)     (KB/s)

---------  ---------    ---------  ---------

   8263189     134044      8282891     134135

  10303281     138184     10277478     138871

   7390737     124244      7407889     123662

Should is not happen inside the box? (This is Avamar root-2-root btw).

Regards

Oliver