A PHP Acelerator is a tool that will enhance the performance of web applications written for the PHP scripting language. The free Alternative PHP Cache (APC) is distributed as a PEAR package.
If you run your own LAMP server with PHP applications, then please install it.
Installation
Assuming you already have Apache2 and PHP5 (with dev extensions so PECL can run phpize), it's as easy as
# make sure we have the development headers and apxs2 binary for threaded versions of apache2
sudo apt-get install apache2-threaded-dev
# install the APC extension
sudo pecl install APC
# pecl would have updated my php.ini file automatically, but it did not know where to look.
# set it for future reference
sudo pear config-set php_ini /etc/php5/apache2/php.ini
# do the configuration of php settings file myself
sudo vi /etc/php5/apache2/php.ini
# test and restart apache
sudo apache2ctl configtest
sudo apache2ctl graceful
# make a symbolic link to the system front-end
cd /var/www
sudo ln -s /usr/share/php/apc.php
Notes
APC, aside from speeding up your website, also provides a storage mechanism outside the traditional cookie/session mechanism. So, you could set an application variable or constant and (assuming that the cache is not cleared, etc.) retrieve that value from another context.