Mobile app performance testing provides several key benefits: 1) It helps improve an app's scalability by analyzing how the app performs under standard and high loads to ensure it can handle increased traffic and users. 2) It helps reduce costs by identifying bugs, bottlenecks and errors before launch to prevent downtime that could impact revenue. 3) It helps optimize user engagement by testing an app's onboarding process and performance across different devices and platforms. 4) It helps validate that an app's features and functions deliver as intended without impacting work speed or quality.