This article covers how to set custom php.ini in FastCGI. Basically, FastCGI is the best to manage resources for a high traffic site in shared servers.
To create Custom php.ini with PHP5 under FastCGI:
1. First open .htaccess for the account in question and add the following lines to the bottom of the file:
AddHandler php5-fastcgi .php
Action php5-fastcgi /cgi-bin/php5.fcgi
2. Next, you'll need to source your main server php.ini which is located in /usr/local/lib/. Also note that it needs to have the correct ownership so we'll take care of that too:
cp -a /usr/local/lib/php.ini .
chown user:user php.ini
3. Next we need to create the wrapper script. Create a file in your current directory (cgi-bin) called php5.fcgi as defined above and add the following:
4. Finally, make sure the ownership and permissions are correct on this file:
chown user:user php5.fcgi && chmod 0755 php5.fcgi