Unable to reproduce a question's dialog freeze after user response.

dialog_dismiss_latency.dart

// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      debugShowCheckedModeBanner: false,
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;

  void _incrementCounter() {
    setState(() {
      _counter++;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text(
              'You have pushed the button this many times:',
            ),
            Text(
              '$_counter',
              style: Theme.of(context).textTheme.headline4,
            ),
            RaisedButton(
              shape: StadiumBorder(),
              child: Text("Post New Request"),
              onPressed: () async {
                if (true) {
                  bool flag = await showDialog(
                      context: context,
                      builder: (BuildContext context) {
                        return AlertDialog(
                          title: Text('Are you sure?'),
                          content: Text("Are you sure to post new request?"),
                          backgroundColor: Theme.of(context).primaryColor,
                          actions: <Widget>[
                            RaisedButton(
                                shape: StadiumBorder(),
                                child: Text("Yes, Post request"),
                                onPressed: () =>
                                    {Navigator.of(context).pop(true)}),
                            RaisedButton(
                              shape: StadiumBorder(),
                              color: Theme.of(context).errorColor,
                              child: Text("No",
                                  style: TextStyle(color: Colors.white)),
                              onPressed: () => Navigator.of(context).pop(false),
                            )
                          ],
                        );
                      });
                  print(flag);
                  if (flag) {
                    Future.delayed(Duration(seconds: 5))
                        .then((_) => print('Service responded'));
                    
//                     for (int i = 0; i < 1000; i++) {
//                       RequestsService.addRequest(request).then((value) => {});
//                     }
                  }
                }
              },
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ),
    );
  }
}