Salesforce Performance Engineer interview questions

It was quick, 1 phone screen interview, after that onsite interviews(6 interviews onsite). Questions weren't too difficult but not very easy as well had to think, mostly related to performance in 3-tier architecture find areas that can be bottlenecks, some OO concepts, database indexing and sql queries. Overall the interview questions are position based, not very difficult although the test is tedious to finish but not impossible. With some Java programming practice one can clear the interviews.