We've done a few things thus far with this JIRA...
o We've modified the build pom.xml to use the Java 6 compiler exclusively.
o We've modified the source/target levels for the compiler to be 1.6.
o My patch has removed the ConcreteClassGenerator usage for the JDBC3/4 interfaces.
With these build and coding updates, the performance improvement is minimal (at best). Our code is a little cleaner, but it doesn't seem to have affected performance all that much.
Couple these results with the removal of Java 5 runtime support, and I think we have to ask whether this is the right thing to do at this point. Although Java 5 is (or is going) out of service, we could possibly be alienating some potential customers by limiting us to Java 6. And, for what benefit?
Maybe we should still move to Java 6 as our official build compiler, but go back to the source/target levels of 1.5 to be compliant with the old runtime.
I know we had this [DISCUSS] item on our mailing list, but given the results, maybe we should reconsider the intent of this JIRA.