Task to bring down rebuilds of customContainer from 42 to 1

main.dart

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData.light(),
      darkTheme: ThemeData.dark(),
      themeMode: ThemeMode.system,
      home: const Home(),
    );
  }
}

class Home extends StatelessWidget {
  const Home({Key? key}) : super(key: key);

  final Widget customContainer = const CustomContainer();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text("Grid"),
      ),
      body: GridView(
        shrinkWrap: true,
        gridDelegate: const SliverGridDelegateWithFixedCrossAxisCount(
          childAspectRatio: 1,
          crossAxisCount: 7,
          mainAxisExtent: 40,
          crossAxisSpacing: 5,
          mainAxisSpacing: 5,
        ),
        children: List.generate(42, (index) {
          return customContainer;
        }),
      ),
    );
  }
}

class CustomContainer extends StatelessWidget {
  const CustomContainer({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Container(
      color: Colors.pink,
      height: 40,
      width: 40,
    );
  }
}