I can give you some information about what we are using to cache our database data (this mechanism work very well with Oracle). For all our db access we are using hibernate but with OScache. You can find information there http://www.opensymphony.com/ but I don't know if it is usable by you......
Yes this is a project we have (perhaps more with Apache OJB - http://db.apache.org/ojb/ - and JCS - http://jakarta.apache.org/turbine/jcs/ - as we are more focused on integrating the whole Apache stack, but the effet will be the same).
However:
A) Jahia is now 5 years old and such tools were not initially existing, so we sometimes have to live with the existing pieces of code (even if we would used other more performing layers today if we restarted the project from scratch)
B) As Serge mentionned it, such a refactoring will not happen overnight and will require time (... and then money)
C) most of the Jahia users prefer usually developing or sponsorizing new functional features rather than low-level refactoring tasks (quite a shame but also quite understandable as low level optimizations are more difficult to explain and to deal with the management team). However Jahia is released under a collaborative source license which allows you 1) to influence next Jahia developments and 2) to get license credits for all your direct or indirect contributions in the community. So if you think it is important for you, feel free to try to sponsorize it or to develop it internally (... and if I am not wrong we are right now negociating such a generic development budget with the European Parliament in order to let you (them) choose and decide which will be the next key features you (they) want to see refactored or added inside next releases of Jahia... So perhaps such a refactoring will be one of these future collaborative projects!)
Best Regards
St�phane
