Sorry i guess this post got posted twice.. "JavaRanch » Java Forums » Java » Performance ". this will be the correct path.
but can somebody seriously help me out and can also provide a proper explaination.
Creating and calling the interface to JNI methods certainly will consume some CPU time so your C or C++ would have to be faster to justify that.
If multiple clients can access the application, you would have to manage the separate requests. If database access is involved in the business logic that CPU time would probably be much more important than execution of logic code so the language won't matter.