使用auto_prepend_file会影响性能吗？

Comparing the three alternatives below, how does auto_prepend_file impact performance?

1. .htaccess - php_admin_value auto_prepend_file /path/to/file.php
2. httpd.conf - php_admin_value auto_prepend_file /path/to/file.php
3. php.ini - auto_prepend_file = "/path/to/file.php"
4. included on every php script - require_once "/path/to/file.php";

Are all generally equal in performance?

Are there best practices to consider?