src/share/classes/javax/swing/DefaultComboBoxModel.java:51: public DefaultComboBoxModel(final Object items[]) {
    src/share/classes/javax/swing/DefaultComboBoxModel.java:52: objects = new Vector();
    src/share/classes/javax/swing/DefaultComboBoxModel.java:53: objects.ensureCapacity( items.length );

creates a default-sized Vector and then resizes it. That probably drops the default-sized backing array on the floor and allocates a new one. It would be more efficient to create the Vector with the appropriate size. I don't know what the average size of the items array is to the DefaultComboBoxModel constructor. If that array is typically small, then maybe this isn't a problem.