Delay in creation of a shipment

Environment:

JDE v 8.10

Using Transportation management module.

DB2, I series IBM

Problem:

Occasionally we see delays in the creation of a shipment during order entry. Order entered at 13:30 shipment did not appear to the users until after 16:00.

Does anyone know what may be causing this delay and perhaps what we can do to minimize the delay?  This happens infrequently that we are aware of.  Normally shipments are created during order entry during the P4210 End doc rather quickly.