title: DotNetZip performance issue, but only on one specific server
body: <p>I'm having a wierd performance problem with the DotNetZip library.</p>
  
  <p>In the application (which runs under asp.net) i'm reading a set of files from the database and packs them on-the-fly into a zip file for the user to download.</p>
  
  <p>Everything works fine on my development laptop. A zip file being about 10MB with default compression rate takes something around 5 seconds to finish. However, on the dev server at the customer, the same set of files takes around 1-2 minutes to compress. I've even experienced even longer times, up to several minutes. The CPU utilization is 100% when the zipping is running, but otherwise it stays around 0%, so it's not due to overload.</p>
  
  <p>What's even more interesting is that on the production server, it takes something about 20 seconds to finish.</p>
  
  <p>Where should I start looking?</p>
  
  <p>Some hardware specs:</p>
  
  <p><strong>My Laptop</strong></p>
  
  <p>Development environment running on a virtualbox with 2 cores and 4GB RAM dedicated.</p>
  
  <ul>
  <li>Core i5 M540 2,5GHz</li>
  <li>8 GB RAM</li>
  <li>Win7</li>
  </ul>
  
  <p><strong>Dev Server</strong></p>
  
  <p>According to properties dialog on My Computer (probably virtualized)</p>
  
  <ul>
  <li>Intel Xeon 5160 3GHz</li>
  <li>540MB RAM</li>
  <li>Windows 2003 Server</li>
  </ul>
  
  <p>Task Manager Reports Single Core</p>
  
  <p><strong>Production Server</strong></p>
  
  <p>According to properties dialog on My Computer (probably virtualized)</p>
  
  <ul>
  <li>Xenon 5160 3GHz</li>
  <li>512MB RAM</li>
  <li>Windows 2003 Server</li>
  </ul>
  
  <p>Task Manager Reports Dual Core</p>
  
  <p><strong>Update</strong>
  The servers are running on a VMWare host. Found the VMWare icon hiding in the taskbar.</p>