APC (or Alternate PHP Cache) is a popular PHP PECL extension that can be used for PHP op-code caching. It is very stable and can significantly reduce page rendering times. It works by caching the PHP binaries, so that PHP doesn’t have to compile them on every request.
Installation is simple:
1. Use yum to install necessary packages.
# yum install php-pear php-devel httpd-devel pcre-devel