Not sure if this helps bit I did find this: http://www.imminentweb.com/technologies/tune-apc-improve-php-performance
Note though one of the responses further down the page: http://www.imminentweb.com/technologies/tune-apc-improve-php-performance#comment-68
I don't know if this is valid information though so hopefully someone will confirm.
Having installed APC for PHP does not automatically improve the performance. You have to adjust the parameters. At the very least, change these values:
apc.ttl="7200"
apc.user_ttl="7200"
apc.shm_segments="3"
apc.shm_size="90"
Setting apc.ttl and apc.user_ttl to none-zero can ensure that the cached php code gets refreshed at the given number of seconds without filling up the memory with stale entries.
The number assigned to apc.shm_size is the size of each shared memory segment in MB. To find the Linux kernel's maximum shared memory size, do
# cat /proc/sys/kernel/shmmax
If you already set the apc.shm_size to the maximum allowed size, then raising the value of apc.shm_segmentswould be the next thing to do.
Of course you can always raise the maximum size of a shared memory segment, using sysctl. Do this only when you know what you are doing. Run "man sysctl" for more information.
Note though one of the responses further down the page: http://www.imminentweb.com/technologies/tune-apc-improve-php-performance#comment-68
I don't know if this is valid information though so hopefully someone will confirm.