For a lot of New Relic customers, bad user experience is due page loading - heavy/erroneous javascript, etc. It is worth reading up on this topic! My answer was not the one she was looking for - coming from a data heavy background (ATMs, payments, etc), a lot of issues happen in the database, sometimes due to locking and sometimes poor resource maintenance. I expanded on why that was my experience and the factors that led to it - social and mechanical.