> So my first question is, does the term "GA" means 4.4.0GA is a more mature release than v4.2.3.SP7 ?
GA releases are basically x.x.0 ones - the first stable, fully tested release for a particular version. The SP (service pack) releases are bug fixes to the same line. 4.2.3.SP7 is the 7th community bug fix release on the 4.2.3.GA base. In so far as 4.4.0.GA has all the relevant fixes from the 4.2.3.SP line and a bunch of new stuff too, it is more mature. On the other hand 4.4. has been out in the world for less time and there may be new issues we've not spotted and squished yet. By the way, you should prefer AS 5.1.0 which uses JBossTS 4.6.1 rather than the 5.0.1 release.
The big changes in the transaction system as far as the app server is concerned are the introduction of full support for the JTS and XTS. We do keep an eye on performance, both between our own releases and relative to alternative products, but it's not our main focus for this release. Of course the performance of the app server is also affected by changes in other components, such as the EJB container and JCA. The only way you are going to know for sure how things have changed is to run the same app in both versions of the server and see what happens. Drop by the performance tuning forum if you have specific questions.
Thank you very much for quick response, the information is very useful!
I am also reading posts in performance tuning forum. :-)