I remember quiet a few people mentioned a significant speed up when trying
to run applications on the latest JDK 1.4.

It is interesting that I had a totally different experience lately. I just
completed JDK 1.3 compatibility work with Cayenne and ran a few performance
tests on Windows using 1.3 and 1.4 JRE's from Sun. The results showed that
1.3 *consistently* outperformed 1.4 by 20-40%.

Now, I know that Sun's main "performance improvement" was in the area of
reflection API, and Cayenne doesn't use much of that unlike WebObjects KVC.
But 1.4 slowdown is still bizarre. The fact that it is showing in many
different unrelated parts of my unit test suite makes me belive that the
implementation of some basic class like "String" or "StringBuffer" may be
responsible.

Soon I hope to get hold of a licensed commercial profiler that may help to
establish this for sure. But before I ever try digging into it I wonder if
anyone else have experienced similar behavior, or is it simply that I need
to get more sleep? :-)