flutter-performance

From README

Flutter Performance Hold a steady 60 fps ( s.field). A HUD counter tick must never rebuild a heavy sibling. Rebuild scope is the single biggest lever on build-thread cost. Lazy everything long. ListView.builder / GridView.builder / slivers for variable or unbounded content. ListView(children: items.map(...).toList()) builds every off-screen row up front — refuse it for anything not tiny and fixed. No expensive work in build(). No jsonDecode, sort, regex, DateTime math, file/network, or large allocation — build() may run every frame. Compute in the Notifier/ViewModel once and cache the result in immutable state. Heavy CPU off the UI isolate. Parse large payloads, process images, crunch numbers in compute() or a spawned Isolate. Blocking the UI thread is guaranteed jank; the raster thread cannot save you. Size image decode to the display slot. cacheWidth/cacheHeight or ResizeImage, correct asset resolutions, precacheImage for above-the-fold art.