Http download is 3x times slower on Web vs Desktop

[tomekit]

Steps to reproduce

Run code: flutter run --release on Web then click a button, it will download ~18MB file.
Repeat tests on non-web (e.g. desktop platform), download speed shall be much higher.

On my ~40Mbps download connection, Linux maxes out download speed.
On Web speed seem to be throttled for some reason.

Linux

Download file https://cjx45haf.s3.kapsa.io/d4c0f74e-9ef9-40c6-aa27-e2e4bdeafe34/file_example_MP4_1920_18MG.mp4?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=1C6RoVNL9skDTFN1A%2F20240409%2Fus-east-1%2Fs3%2Faws4_request&X-Amz-Date=20240409T093551Z&X-Amz-Expires=604798&X-Amz-SignedHeaders=host&X-Amz-Signature=4fa81af1530666dbed1e942e63e888f7b221c4e1a41f482d1d642798fd1e3824
flutter: Downloaded 17839845 in 3603ms

Web

Download file https://cjx45haf.s3.kapsa.io/d4c0f74e-9ef9-40c6-aa27-e2e4bdeafe34/file_example_MP4_1920_18MG.mp4?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=1C6RoVNL9skDTFN1A%2F20240409%2Fus-east-1%2Fs3%2Faws4_request&X-Amz-Date=20240409T093551Z&X-Amz-Expires=604798&X-Amz-SignedHeaders=host&X-Amz-Signature=4fa81af1530666dbed1e942e63e888f7b221c4e1a41f482d1d642798fd1e3824
Downloaded 17839845 in 11907ms

Code sample

Code sample

import 'dart:async';
import 'package:flutter/material.dart';
import 'package:http/http.dart' as http;

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

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
        useMaterial3: true,
      ),
      home: const MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({super.key, required this.title});

  final String title;

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  void activateDownload() async {
    final url = 'https://cjx45haf.s3.kapsa.io/d4c0f74e-9ef9-40c6-aa27-e2e4bdeafe34/file_example_MP4_1920_18MG.mp4?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=1C6RoVNL9skDTFN1A%2F20240409%2Fus-east-1%2Fs3%2Faws4_request&X-Amz-Date=20240409T093551Z&X-Amz-Expires=604798&X-Amz-SignedHeaders=host&X-Amz-Signature=4fa81af1530666dbed1e942e63e888f7b221c4e1a41f482d1d642798fd1e3824';

    List<int> buffer = [];
    print('\n1) downloadBytesSimple');
    print('\nDownload file $url');
    await downloadBytesSimple(buffer, url);
  }

  static Future<void> downloadBytesSimple(List<int> buffer, String url) async {
    var headers = {
      'Cache-Control': 'no-cache'
    };

    var startTime = DateTime.timestamp();
    final response = await http.get(Uri.parse(url), headers: headers);
    print('Downloaded ${response.contentLength} in ${DateTime.timestamp().difference(startTime).inMilliseconds}ms');
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        backgroundColor: Theme.of(context).colorScheme.inversePrimary,
        title: Text(widget.title),
      ),
      body: const Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text('You have pushed the button this many times:'),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () {
          activateDownload();
        },
        tooltip: 'Increment',
        child: const Icon(Icons.add),
      ),
    );
  }
}

What target platforms are you seeing this bug on?

Web

OS/Browser name and version | Device information

Version 123.0.6312.58 (Official Build) (64-bit)
Ubuntu 23.10

Does the problem occur on emulator/simulator as well as on physical devices?

Yes

Logs

Logs

[Paste your logs here]

Flutter Doctor output

Doctor output

[✓] Flutter (Channel stable, 3.19.5, on Ubuntu 23.10 6.5.0-27-generic, locale en_US.UTF-8)
    • Flutter version 3.19.5 on channel stable at /opt/flutter
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision 300451adae (12 days ago), 2024-03-27 21:54:07 -0500
    • Engine revision e76c956498
    • Dart version 3.3.3
    • DevTools version 2.31.1

[✓] Android toolchain - develop for Android devices (Android SDK version 34.0.0)
    • Android SDK at /home/tomek/Android/Sdk
    • Platform android-34, build-tools 34.0.0
    • ANDROID_HOME = /home/tomek/Android/Sdk
    • Java binary at: /opt/android-studio/jbr/bin/java
    • Java version OpenJDK Runtime Environment (build 17.0.7+0-17.0.7b1000.6-10550314)
    • All Android licenses accepted.

[✓] Chrome - develop for the web
    • Chrome at google-chrome

[✓] Linux toolchain - develop for Linux desktop
    • Ubuntu clang version 16.0.6 (15)
    • cmake version 3.27.4
    • ninja version 1.11.1
    • pkg-config version 1.8.1

[✓] Android Studio (version 2023.1)
    • Android Studio at /opt/android-studio
    • Flutter plugin version 76.3.3
    • Dart plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/6351-dart
    • Java version OpenJDK Runtime Environment (build 17.0.7+0-17.0.7b1000.6-10550314)

[✓] VS Code (version 1.78.2)
    • VS Code at /usr/share/code
    • Flutter extension can be installed from:
      🔨 https://marketplace.visualstudio.com/items?itemName=Dart-Code.flutter

[✓] Connected device (2 available)
    • Linux (desktop) • linux  • linux-x64      • Ubuntu 23.10 6.5.0-27-generic
    • Chrome (web)    • chrome • web-javascript • Google Chrome 123.0.6312.58

[✓] Network resources
    • All expected network resources are available.

• No issues found!

Originally posted here: flutter/flutter#146494