Update: APC 3.1.2 has been released at http://pecl.php.net/get/APC-3.1.2.tgz
 so same instructions as below just replace 3.0.14 with 3.1.2
APC Cache http://pecl.php.net/package/APC seems to work well with PHP 4.4.1 (you should be running PHP 4.4.1 and nothing lower due to security fixes etc).

Notes on installing Alternative PHP Cache (APC):

  1. Download and istall:
    $ wget http://pecl.php.net/get/APC-3.0.14.tgz
    $ tar -xvzf APC-3.0.14.tgz
    $ cd APC-3.0.14
    $ phpize
    $ ./configure --enable-apc
    $ make
    # make install
  2. Add the below lines to the php.ini:
    extension=/path/to/apc.so
    apc.enabled=1
    apc.shm_segments=1
    apc.optimization=0
    apc.shm_size=128
    apc.ttl=7200
    apc.user_ttl=7200
    apc.num_files_hint=1024
    apc.mmap_file_mask=/tmp/apc.XXXXXX
    apc.enable_cli=1
  3. Restart apache:
    # service httpd restart
  4. Check phpinfo() to see if APC is enabled.
  5. Copy the “apc.php” admin file in the source directory to a password protected web site directory. Edit “apc.php” top line to change password to something different from default.