Hi, I have some enterprise apps running on Java 1.4. They mostly invoke Stored Proces on DB, Parse XML files (Not too large files, at the most few megs), read/write from/to disk. We have a requirement where now we have to migrate these apps to Java 6(No code changes to be done at all). My questions: If I dont recompile my apps under Java 6 and just run them with it, will it work fine (I know they 'should'). But if somebody thinks other way round, could you kindly share your thoughts please? More important question is - Will it have any perfomance impact?. As in, App compiled on 1.4 and running on 1.6 vs App compiled and running on 1.6. Is 1.6 gonna do any bytecode optimization for the same old peace of code compared to 1.4? Many Thanks js