When configuration php-fpm you are able to configure it using ports or sockets.
The best thing to do is configure with socks as this avoids the networking stack associated with ports.

This means that php-fpm will be using files (sockets) to run which could be considered slower because of potential slow HDDs however the files are mostly stored in RAM so it makes accessing them significantly quicker.

grep "pm.max_spare_servers" /etc/php-fpm.d/www.conf

ps -eo cmd,pid,pcpu --sort:-pcpu | grep -v grep | grep -c php-fpm