The document describes the process of performance tuning for a database application. It presents a case study where a GUI screen was taking too long to load due to an inefficient query. The case study outlines identifying the problematic query, investigating solutions, replacing the query with a tuned version, and measuring the results. The document also provides an overview of database performance concepts like response time, wait time, and throughput. It describes different components involved in SQL processing like the parser, optimizer, row source generator, and execution plan.