Some PHP-FPM parameters can be tuned for better performance:

pm.max_children – used to set the total number of processes allowed
pm.max_requests – sets the execution time of each child process to curb memory leaks
pm.max_spare_servers – sets the maximum number of idle server processes
pm.start_servers – number of child processes created on startup is defined by this
pm.process_idle_timeout – number of seconds an idle process will be alive
pm.min_spare_servers –  minimum number of idle processes

The PHP-FPM configuration file is available in /etc/php-fpm.conf or based on the service path. File looks like:

listen.allowed_clients =
pm = dynamic
pm.max_children = 5
pm.start_servers = 2
pm.min_spare_servers = 2
pm.max_spare_servers = 5
pm.max_requests = 150

Do not to set very high values for these PHP-FPM parameters, to get maximum performance because if there are not enough resources, high values can crash your server.