The Alternative PHP Cache (APC) is a free and open opcode cache for PHP. Its goal is to provide a free, open, and robust framework for caching and optimizing PHP intermediate code. Besides being a opcode cache it provides a user cache for storing application data.
# Login to the server as root and then
eg : wget http://pecl.php.net/get/APC-3.0.19.tgz
# Extract it
tar -xzf APC-3.0.19.tgz
./configure --enable-apc --enable-apc-mmap --with-apxs --with-php-config=/usr/local/bin/php-config
Check php.ini file path by using following command
php -i | grep php.ini
This will usually return /usr/local/Zend/etc/php.ini on a server that has Zend optimizer installed. Now edit php.ini and add the APC extension.
Scroll down to the bottom and add the fallowing before the lines about the zend optimizer (They start with [Zend])
# Restart Apache
service httpd restart