Some generic parts of Swing code heavily use instanceof which can requires classes to be resolved
and will trigger loading of tested classes.

E.g. Notepad.jar loads JTable, JPasswordField, JTextField, JComboBox, JInternalFrame and some other unneeded classes. This mostly happens because of instanceof checks in the LayoutFocusTraversalPolicy.

This problem lead to increased size of minimal Swing core needed to run simple Swing applications/applets.
Total size of these (not needed) Swing class files is about 100k for Notepad.
Running
  appletviewer -J-verbose:class demo\applets\ArcTest\example1.html
shows that JComponent/JPanel are loaded.

This creates additional unneeded hard dependency between different subsystsems.
Also JComponent class is fairly large (over 40k).

We should avoid loading classes unless they are needed.