We recently conducted performance testing to help us determine best practices for Magento optimization; we documented our results in a free white paper. Here are some of the highlights:
An optimized Magento Enterprise Edition configuration can support more than 350 million catalog views and 487,000 orders per day.
Optimizing a standard 2+1 server configuration with Varnish or Nginx can significantly improve response times.
With proper server configuration and enhanced caching, businesses can maximize hardware efficiency while supporting more customers and transactions.