Flutter Isolates & Compute Complete Guide — Keep Your UI Smooth with Background Processing Flutter runs on a single thread (Dart VM). Heavy work on the main thread drops frames and freezes your UI. Isolates and compute let you run expensive operations in the background while keeping 60fps. Dart's Concurrency Model Dart uses Isolate-based concurrency: Main Isolate : UI rendering + user input Spawned Isolates : Heavy computation, JSON parsing, image processing Communication : Message passing via SendPort / ReceivePort No shared memory : Each Isolate has its own heap compute() — The Simplest Option // Parse large JSON in the background Future < List < Product >> parseProducts ( String jsonString ) async { return compute ( _parseProductsIsolate , jsonString ); } // Must be top-level or static List < Product > _parseProductsIsolate ( String jsonString ) { final List < dynamic > data = jsonDecode ( jsonString ); return data . map (( json ) = > Product . fromJson ( json )) .…