Today I have faced an error while accessing the domain, also the response is too slow.
[Thu Aug 22 13:05:06 2013] [warn] [client 200.150.249.63] mod_fcgid: can’t apply process slot for /usr/local/cpanel/cgi-sys/php5, referer: http://www.domain.com/tracking/index.php
This issue commonly occur due to lower value of MaxRequestsPerProcess.
Solution :-
#vim /usr/local/apache/conf/php.conf
MaxRequestsPerProcess 1000
DefaultMaxClassProcessCount 120
IdleTimeout 60
MaxProcessCount 2000
IPCCommTimeout 40
IPCConnectTimeout 10
MaxRequestLen 10240000
Reference :
http://httpd.apache.org/mod_fcgid/mod/mod_fcgid.html#fcgidspawnscoreuplimit