I have come across the Performance Engineer position. To describe the responsibilities, one will have to analyze, benchmark, optimize the performance of the applications.
Its not a routine coding activity that the developers do but at the same time,you will need good understanding of
JEE, application architecture and the integration technologies used in your project.
In my opinion, its a work in which you may have direct interaction with the senior management and the customer team (if you are working in service sector), which may help you in the long run. You will have to check these details with the manager who took your interview.
If you are a person who wishes to write loads of code then this position may not be for you.