App launch speed is crucial for setting expectations of overall quality and impact on long-term retention. Slow launches, even repeat slow ones, can negatively affect user experience and should be monitored to identify potential issues. UI responsiveness is also vital, with users expecting quick and accessible experiences that may abandon the app if they encounter slow or hanging performance. Network performance is another key aspect, as slow network calls can cause frustration and should be tracked to understand client-side request response times. Screen loading times are essential for a smooth user experience, while execution traces help identify custom client-side logic issues. The Apdex metric provides an industry-standard way to measure user satisfaction based on speed and stability, allowing teams to align around a standardized quality metric and set targets for improvement.