Since i keep this blog for my own records, i could not find the post about installing APC.
So, here are the quick steps since i don’t have enough time today to explain the whole installation
1- Install the tools
apt-get install apache2-threaded-dev php5-dev php-pear make
pecl install apc
Add the file /etc/php5/conf.d/apc.ini with the contents extension=apc.so (And any other relevant settings)
vi /etc/sysctl.conf Add the line kernel.shmmax = 67108864 (or whatever space you need)