in reply to Perl, Java, MySQL?
an application written for mobile apps in Java using a MySQL database
This leaves open questions. Depending on how the application is partitioned, i.e. what runs where, and if changes can be made to server-side Java, if any.
If the app was developed with the Android SDK and it connects to a server where mySQL runs with no server-Side Java you just need a database connect:)
If there is server-side Java (there are various flavours ranging from "simple" to Enterprise Edition) there are severalways. It very much depends how it is implemented and if changes can be made to it.
Using one of the mentioned alternatives will likely lose you more than "some performance". I propose a different approach. You can easily expose Java classes as Web services and this can be integrated a lot easier!