The Service Desk object manager, or domsrvr, is responsible for building the object repository for Service Desk to use. As such, it's the Service Desk process which will most likely take the long to start up, and Service Desk will not be usable until this start up is complete.
If the domsrvr start up is slow, you should first of all check if MLISTS/RLISTS are turned on for any customised tables.
MLIST - A Master list containing an in-ram references to all of the objects in the factory. This list is kept in sync with the data repository.
RLIST - A Restricted Master list containing a subset of the objects in the factory. The subset is defined by a where clause. Other than this where clause, the RLIST is the same as the MLIST.
MLISTS and RLISTS are defined in majic files:
MLIST ON | OFF ;
RLIST ON | OFF ;
REL_ATTR code ;
COMMON_NAME sym ;
FUNCTION_GROUP "admin" ;
and part of tuning the domsrvr is deciding whether to have MLISTS and RLISTS or not. If they are defined, they can speed application access and display, but they can also use up lots of domsrvr resources. The start up time of the domsrvr has known to be severely reduced by disabling MLISTS and RLISTS for custom tables.