When using the Swing demo application Stylepad (as a reproducable test case) you can observe excessive memory usage, making the application not viable as a release product. Reproduce by the following:
(NT 4 SP4, JDK 1.2.2 FCS)
i) open task manager
ii) run Stylepad application
iii) cut all of alice text out
iv) copy some 96k text from ie. Notepad
v) paste using menu

You can see that over 20MB is taken up by this procedure and it is linear upon pasting greater text sizes.

I believe this to be associated with bug : 4203912.