Performance monitoring
Performance monitoring samples the device while your app runs and charts the results. Read the counters carefully: the same number can mean different things.
Start a capture
Section titled “Start a capture”- Select the device and choose an app.
- Open Performance.
- Click Start, use the app on the device, then click Stop.
The chart updates in real time. The saved capture is what you keep.
Counters
Section titled “Counters”Shown as a percentage of one core. Values above 100% are normal on multi-core devices and mean more than one core is busy. Look at the pattern: a steady 40% while scrolling is a sustained workload, while a 5% baseline that spikes to 90% for 200 ms is a stall.
GPU utilization as a percentage. High GPU use with a stable frame rate is fine. High GPU use with a falling frame rate means the app is render-bound. Common causes are overdraw, too many layers, and effects that require offscreen rendering.
Memory
Section titled “Memory”The process’s resident memory footprint. Watch the trend, not the value. A sawtooth that keeps returning to the same baseline is a working cache. A staircase that never comes back down is a leak. iOS terminates processes that use too much memory, and the result looks like a crash with no exception in the report.
Frame rate
Section titled “Frame rate”Frames presented per second. The average alone is not useful; the drops matter. See FPS and jank.
Network
Section titled “Network”Bytes sent and received by the process. This counter measures volume, not content. A screen that downloads several megabytes when it opens shows up here immediately. To inspect requests, use SniffMaster.
Energy
Section titled “Energy”An energy-impact value, not a milliamp-hour measurement. Use it to compare, for example this build against the last one, or your app against another. For energy use over several days, see usage history.
Compare two apps
Section titled “Compare two apps”Capture the same interaction in both apps and compare the two runs side by side. Whether an app is “heavy” only makes sense relative to something else.
Mini-programs
Section titled “Mini-programs”A mini-program runs inside a host app. If you select the host, you measure the host and everything running in it. To measure only the mini-program, select its own process.
Tips for accurate captures
Section titled “Tips for accurate captures”- Repeat the same interaction. Scroll the same list the same distance. Captures of different interactions cannot be compared.
- Let the device settle. The first seconds after launch are dominated by startup work.
- Watch the temperature. A hot device throttles, and a throttled capture reflects heat rather than code.
- Test on typical hardware. Your users are not all on the latest flagship.
Free and VIP features
Section titled “Free and VIP features”The performance overview is free. Performance charts can be tried for 1 minute each time you launch KeyMob. Full access to charts and performance history requires VIP. See pricing.