title: Download big files with QNetworkreply::readAll freeze for a few seconds
body: <p>I used example like doc <a href="http://doc.qt.io/qt-4.8/qnetworkaccessmanager.html" rel="nofollow noreferrer">http://doc.qt.io/qt-4.8/qnetworkaccessmanager.html</a></p>
  
  <p>I create a <code>startDownload</code>:</p>
  
  <pre><code>connect(pushButton, SIGNAL(clicked(bool)), this, SLOT(startDownload(bool)));
  </code></pre>
  
  <p>In <code>startDownload(bool)</code> I put this:</p>
  
  <pre><code>file = new QFile("C:/foo/bar/bigfile.7z");
  file-&gt;open(QIODevice::WriteOnly);
  
  QNetworkRequest request;
  request.setUrl(QUrl("http://localhost/bigfile.7z"));
  request.setRawHeader("User-Agent", "MyOwnBrowser 1.0");
  
  QNetworkReply *reply = manager-&gt;get(request);
  
  connect(reply, SIGNAL(readyRead()), this, SLOT(slotReadyRead()));
  connect(reply, SIGNAL(error(QNetworkReply::NetworkError)),
          this, SLOT(slotError(QNetworkReply::NetworkError)));
  connect(reply, SIGNAL(sslErrors(QList&lt;QSslError&gt;)),
          this, SLOT(slotSslErrors(QList&lt;QSslError&gt;)));
  </code></pre>
  
  <p>In <code>slotReadyRead</code> I put this:</p>
  
  <pre><code>file-&gt;write(reply-&gt;readAll());
  </code></pre>
  
  <p>But when the download arrives at the end there is a small freezing 2 seconds and then returns to normal and the download is complete. This problem only occurs if the file I'm trying to transfer is large.</p>