Render performance is the most typical performance issue that apps face. In order to provide a good user experience, render must be measured over different stages in the app's lifecycle, providing a jank-free experience.
Frames per Second (FPS)
Usually, drawing in mobile devices happens every ~16 ms (depending on the hardware refresh rate). This means that your app should be able to render at ~60 FPS (frames per second). To achieve this, each update to the screen will need to end in less than 16 milliseconds. Below 30 FPS, the user experience will be affected and users will complain.
Render Time (⚠️ Android only)
Every second, several layers are trying to complete drawing and be sent to the hardware. Apptim measures the time taken for each layer to complete drawing, and displays a Render Time chart with MAX and MIN of each second. If MAX > refresh rate, then you will detect a JANK.
Render Lag or Janks (⚠️ Android only)
If a frame took more time than the refresh rate to draw (~16ms), it will be skipped and will miss the opportunity to be displayed on time. When this happens, it is called a jank. This affects user experience especially in animations or when a user is interacting with the UI via typing or dragging a list view.
Activity Times (⚠️ Android only)
Activities are the most important component of an Android app. Understanding and managing the activities lifecycle properly is critical for user experience, as well as measuring the amount of time each activity takes to initialize, inflate and display.