Performance defects refer to issues in a product or system that hinder its ability to function as intended. These defects can manifest as slow response times, crashes, or excessive resource consumption, impacting user experience and overall efficiency. Identifying and addressing these defects is crucial for maintaining quality and reliability. Common causes of performance defects include coding errors, inadequate testing, and insufficient hardware resources. Tools and techniques, such as load testing and profiling, can help detect these issues early in the development process. By resolving performance defects, organizations can enhance user satisfaction and ensure smoother operation of their products.