Proper configuration of Magento Enterprise Edition with the appropriate hardware capabilities and software configuration can lead to a significant improvement in overall system performance. Using Varnish or Nginx as a caching mechanism greatly offloads the application servers from serving dynamic requests. This results in faster response times and allows more requests to be processed by the application server.
This section documents the performance that can be achieved by properly configuring Magento Enterprise Edition. With an optimized configuration, Magento is able to support over 350 million catalog views and 487,000 orders per day with improved response times.
Download the document here.