title: Which PHP opcode cacher should I use to improve performance?
body: <p>I'm trying to improve performance under high load and would like to implement opcode caching. Which of the following should I use?</p>
  
  <ul>
  <li>APC - <a href="http://www.howtoforge.com/apc-php5-apache2-debian-etch" rel="noreferrer">Installation Guide</a></li>
  <li>eAccelerator - <a href="http://www.howtoforge.com/eaccelerator_php5_debian_etch" rel="noreferrer">Installation Guide</a></li>
  <li>XCache - <a href="http://www.howtoforge.com/xcache-php5-apache2-debian-etch" rel="noreferrer">Installation Guide</a></li>
  </ul>
  
  <p>I'm also open to any other alternatives that have slipped under my radar.</p>
  
  <p>Currently running on a stock Debian Etch with Apache 2 and PHP 5.2</p>
  
  <p><strong>[Update 1]</strong></p>
  
  <p>HowtoForge installation links added</p>
  
  <p><strong>[Update 2]</strong></p>
  
  <p>Based on the answers and feedback given, I have tested all 3 implementations using the following Apache JMeter test plan on my application:</p>
  
  <ul>
  <li>Login</li>
  <li>Access Home Page</li>
  </ul>
  
  <p>With 50 concurrent connections, the results are as follows:</p>
  
  <p>No Opcode Caching<br>
  <img src="https://i.stack.imgur.com/ueCBW.jpg" alt="No Opcode Caching"></p>
  
  <p>APC<br>
  <img src="https://i.stack.imgur.com/ggqC8.jpg" alt="APC"></p>
  
  <p>eAccelerator<br>
  <img src="https://i.stack.imgur.com/puxe5.jpg" alt="eAccelerator"></p>
  
  <p>XCache<br>
  <img src="https://i.stack.imgur.com/GybYH.jpg" alt="XCache"></p>
  
  <p>Performance Graph (smaller is better)<br>
  <img src="https://i.stack.imgur.com/oXTe9.png" alt="Performance Graph"></p>
  
  <p>From the above results, eAccelerator has a slight edge in performance compared to APC and XCache. However, what matters most from the above data is that any sort of opcode caching gives a tremendous boost in performance.</p>
  
  <p>I have decided to use APC due to the following 2 reasons:</p>
  
  <ul>
  <li>Package is available in official Debian repository</li>
  <li>More functional control panel</li>
  </ul>
  
  <p>To summarize my experience:</p>
  
  <p>Ease of Installation: APC > eAccelerator > XCache<br>
  Performance: eAccelerator > APC, XCache<br>
  Control Panel: APC > XCache > eAccelerator</p>