Many developers face challenges with query performance in applications, especially under high request volumes, potentially impacting databases and APIs. Andres Sacco, a seasoned developer, addressed these issues by demonstrating how query performance problems can arise, particularly with join operations, and proposed methods to diagnose and improve performance using tools like QuickPerf. His discussion included a scenario involving a microservice with performance issues and emphasized the importance of monitoring, profiling, and analyzing system behavior. Sacco also provided insights into tools like JFR, QuickPerf, Gatling, and JMeter, outlining their strengths and weaknesses for performance testing. He shared practical coding examples and best practices for testing and optimizing database queries, highlighting the value of a systematic approach to identify and resolve bottlenecks. The session concluded with a Q&A, where Sacco addressed unexpected database performance challenges, the importance of well-documented test cases, and the potential of chaos testing to enhance database resilience.