Fastest image processing in Java on AS/400

I have written a small program which reads a TIFF file using JIMI and
process (blurr and resize) the individual images before writing them
to individual JPEG files using the Java Graphics and Graphics2D

This is being done in headless mode in 1.4.2, and takes around 5
seconds per JPEG image.

My question is whether anybody has any experiences in which Java
configuration is the best? Is there any optimizations possible on the
iseries platform like the graphics card volatile images in the Sun
JVM, which might allow us to speed up this process which is identical
for each individual image in the batch. Java 1.4.2 and Java 1.5 can
be used.

Thanks for feedback :)

Thorbjørn Ravn Andersen