How do you profile Flutter performance and find jank?

Debug mode is not representative because it disables optimisations and adds assertions. Profile mode keeps AOT compilation and most performance characteristics while enabling tracing. A sixty-hertz frame has about sixteen milliseconds of budget across the pipeline; a hundred-twenty-hertz frame has about eight.

flutter run --profile

• Use DevTools Performance to inspect UI and raster thread timelines
• Enable track widget builds and rebuild stats to find excessive rebuilds
• Check whether jank is on the UI thread or the raster thread before changing code
• Use a physical device for representative GPU and thermal behaviour
• Measure a repeatable scenario and compare before and after with the same build mode

Common root causes

UI-thread jank often comes from large rebuilds, expensive build methods, synchronous JSON parsing or layout thrash. Raster jank comes from large images, saveLayer, shadows, blurs and shader compilation. Impeller reduces shader compilation stutter on supported platforms, but it does not fix oversized textures or overdraw.