flutter_const_optimization.dart

import 'dart:async';
import 'dart:math';

import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      home: Scaffold(
        body: Center(
          child: MyWidget(),
        ),
      ),
    );
  }
}

class MyWidget extends StatefulWidget {
  @override
  _MyWidgetState createState() => _MyWidgetState();
}

class _MyWidgetState extends State<MyWidget> {
  @override
  void initState() {
    super.initState();
    Timer.periodic(Duration(seconds: 1), (_) => setState(() {}));
  }

  @override
  Widget build(BuildContext context) {
    return Column(children: [
      const SomeWidget(),
      SomeWidget(),
    ]);
  }
}

class SomeWidget extends StatelessWidget {
  const SomeWidget();
  @override
  Widget build(BuildContext context) => Container(
        height: 100,
        color: Colors.red.withOpacity(
          Random().nextDouble(),
        ),
      );
}