Trim or Extend takes abnormally long to complete when defaulting to the all entities boundry in a moderate sized 3-view dwg or file (137KB).

The command strokes are: (using right click for enter>)

:ex>, :>, (select line to extend and wait.........)

It does complete but in a time frame that discourages using the command that way.  I'm not sure the difference in command handling between DS11.2 and Acad 2004 but Acad does not hesitate.