This document discusses the evolution from performance testing to performance engineering. Performance engineering is a proactive, shift-left approach that includes systematic techniques and activities in each sprint to meet performance needs. It focuses on design principles, architecture, and detecting bottlenecks early. Performance engineering requires skills in application diagnosis, infrastructure optimization, threading, concurrency, databases, and networks. It aims to deliver fast, efficient systems through a culture where performance is a shared responsibility. Continuous performance testing is important for technical agility and reducing business risks.