Update: APC 3.1.2 has been released at http://pecl.php.net/get/APC-3.1.2.tgz so same instructions as below just replace 3.0.14 with 3.1.2 APC Cache http://pecl.php.net/package/APC seems to work well with PHP 4.4.1 (you should be running PHP 4.4.1 and nothing lower due to security fixes etc).