Right question, Pepe.
I did some raw tests on jdk1.5 overall desktop and java2d performace an it seems that something changed. Looks like the auto-VRAMMING of some images is finally here (at least I suspect..).
The server jvm gives a nice performance boost to my computational intensive code and that's really positive. Sadly the server JVM is not in the JRE distribution...
Well, to be sincere I expected improvements in alpha blending both for speed (drawImage still use software loops) and quality (see the bug at http://developer.java.sun.com/developer/bugParade/bugs/4950176.html
I expected better shapes stroking quality (antialiased outline text looks ugly on win32 (and not on MacOSX)).
I also expected hardware accelerated AffineTransforms.
I keep dreamin'...