iOS UI Rendering Performance

UI rendering performance of an iOS app is measured by observing whether app interactions in key user journeys are natural and instant. The UI rendering app performance of an iOS app is the percentage of slow frames rendered. The percentage of slow frames are the frames taking more than 16 ms to render.

How does it impact user experience

Delay in user interaction, hangs, or hitches can cause user experience issues by making the app feel unresponsive and frustrating for users. These issues can lead to poor user engagement and negatively impact user retention, app reviews, and overall app success.

Threshold Guidelines

Percentage of slow frames in a session <= 25% of overall frames rendered

Recommendations

The following are the recommendations to improve UI Rendering Performance:

• Simplify the app’s view hierarchy and reduce the number of subviews to minimize the rendering workload.
• Optimize images and graphics to reduce their memory footprint and improve rendering speed.
• Use auto-layout constraints and avoid hardcoding frames to improve performance and ensure layout correctness.
• Use Core Animation efficiently and avoid performing heavy animation tasks on the main thread.

Related topics

• View the complete list of performance metrics for iOS