A poorly performing Internet application creates doubt about its
robustness in your user’s mind and often turns the person away.
Lengthy page loads and slow transactions are typical examples. To
help achieve adequate performance levels, you need to ensure that
operational specifications are written during the requirementsgathering phase. Without written specifications or goals, you do not
know whether your application performs acceptably. Operational
specifications are often stated in terms of response times or throughput rates. For instance, a page should load in x seconds, or the application server will complete y credit card transactions per minute.