title: C# speed up webclient download
body: <p>How to speed up downloading html source code of website by url in a loop?</p>
  
  <p>I'm using this code to download, but it's quite slow. (avg download time ~5s per url)</p>
  
  <pre><code>using (WebClient client = new WebClient())
  {
      for (int i = 0; i &lt;= 20; i++)
      {
          var source_code = client.DownloadString(url[i]);
      }
  }
  </code></pre>