I’ve lost count how many times I’ve needed to recompile a new version of APC for PHP on my server, so this mainly serves as a reminder on how to do it for next time.

1. Go to http://pecl.php.net/package/APC and find the latest download link at the time.
2. Login via SSH and go into root login via

   su -

3. Navigate to the source folder:

   cd /usr/local/src

4. wget the latest download from the PHP pecl link above. (i.e. wget http://pecl.php.net/get/APC-3.0.15.tgz)
5. Unzip the archive like so:

   gunzip -c APC-3.0.15.tgz | tar xf -

6. Navigate to the APC folder:

   cd APC-3.0.15

7. phpize the APC folder to make the correct configuration file: /usr/bin/phpize
8. Make the configuration file:

   ./configure --enable-apc --enable-apc-mmap --with-apxs --with-php-config=/usr/bin/php-config

9. Start the compile:

   make

10. Finish and install:

    make install

11. Edit the php.ini file to enable the APC module based on the location provided from the previous command:

    pico -w /usr/lib/php.ini

12. Finally restart apache to see the changes:

    service httpd restart

The important bits you need to put inside php.ini are the extension call like so:

extension = "apc.so"

You then also need to enable and configure APC to your liking. Here’s my setup:

apc.enabled = 1
apc.shm_size = 64
apc.ttl = 3600
apc.user_ttl = 3600
apc.optimization = 0
apc.filters = "-Gallery.*\.class, wp-cache-config, -mint.php"
apc.include_once_override=1
apc.write_lock=1

Other things you need to take into account is your PHP extension_dir setting. This needs to be set right to be able to load the module correctly above.
You should also bear in mind that /usr/bin/phpize and /usr/bin/php-config could be different for your system setup.