Event Loop unloading

eventloop.dart

import 'dart:async';

import 'package:crypto/crypto.dart';
import 'package:flutter/material.dart';

void main() {
  runApp(const MainApp());
}

class MainApp extends StatefulWidget {
  const MainApp({super.key});

  @override
  State<MainApp> createState() => _MainAppState();
}

class _MainAppState extends State<MainApp> {
  bool optimized = false;

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
          child: Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: [
              Switch(
                value: optimized,
                onChanged: (value) {
                  setState(() {
                    optimized = value;
                  });
                },
              ),
              TextButton(
                onPressed: () {
                  final stopWatch = Stopwatch()..start();
                  fetch(optimized).toList().then(
                    (v) {
                      Zone.current.print(
                          'Processed ${v.length} elements in ${stopWatch.elapsedMilliseconds}ms');
                    },
                  );
                },
                child: const Text('Perform Heavy Operation'),
              ),
              const CircularProgressIndicator(),
            ],
          ),
        ),
      ),
    );
  }
}

Stream<String> fetch(bool optimize) {
  // perform operation to get your data
  final data = generateData();
  return Stream.fromIterable(data).asyncMap<String>(
    (e) {
      if (optimize) {
        return Future(() => e);
      }
      return e;
    },
  ).map((event) => sha1.convert(event.codeUnits).toString());
}

// generate string with length of index
Iterable<String> generateData() => Iterable.generate(
      10000,
      (index) => 'a' * index,
    );