php-cgi high load issues

Hi,

For a while now I'm routinely being notified by CSF of high loads on the system, when checking the top records, its always related to httpd + php-cgi

Code:

nobody   3414298  1.9  0.2 259708 38752 ?        S    07:05   1:25  \_ /usr/sbin/httpd -k start
 user1   3444976 72.3  0.8 353384 145592 ?       R    08:19   0:02  |   \_ /opt/cpanel/ea-php56/root/usr/bin/php-cgi
 user1   3444977 67.3  0.8 346376 138812 ?       R    08:19   0:02  |   \_ /opt/cpanel/ea-php56/root/usr/bin/php-cgi
 user2    3444981 98.0  0.5 291536 82480 ?        R    08:19   0:01  |   \_ /opt/cpanel/ea-php56/root/usr/bin/php-cgi
 user3      3444990 53.0  0.3 336792 56268 ?        S    08:19   0:00  |   \_ /opt/cpanel/ea-php56/root/usr/bin/php-cgi
 user4     3444991 60.0  0.3 268440 61372 ?        R    08:19   0:00  |   \_ /opt/cpanel/ea-php56/root/usr/bin/php-cgi
 user2    3444992 45.0  0.2 242000 35672 ?        R    08:19   0:00  |   \_ /opt/cpanel/ea-php56/root/usr/bin/php-cgi
 user3  3444995 47.0  0.2 255160 48376 ?        R    08:19   0:00  |   \_ /opt/cpanel/ea-php56/root/usr/bin/php-cgi
 user2    3444996  0.0  0.1 230724 23752 ?        S    08:19   0:00  |   \_ /opt/cpanel/ea-php56/root/usr/bin/php-cgi
 user5 3444997  0.0  0.1 228956 21404 ?        R    08:19   0:00  |   \_ /opt/cpanel/ea-php56/root/usr/bin/php-cgi

The only common element usually is the sites are wordpress based.
Mysql lives on another system which was done to reduce the load / increase site load times and my thought was perhaps there is a PHP<->MYSQL bottleneck queuing issue.

However checking the mysql server, it seems almost over spec'd and during times of high load on the main cpanel server, mysql server is practically idling, example it has 500 max connections and barely reaches 240 max at its peak.

The cpanel box is a 16 core / 16gb ram system.

Code:

              total        used        free      shared  buff/cache   available
Mem:          16042        4274        2062         801        9704       10461
Swap:         16383           0       16383

Running Cpanel v72.0.9 / Cloudlinux 7.5

I'm almost wondering if its worth putting nginx on the system to see if it would assist, I run a combination of nginx/php-fpm on single site systems that receive high traffic but typically prefer to rely on what cpanel offers out of the box.

This is really bugging me, also during these frequent high load periods, reviewing the sites accesslogs they dont seem to be experiencing mass traffic or any xmlrpc attacks, nothing out of the ordinary.

Hopefully someone might have some suggestions on what to try / might be going on. Open to any/all ideas at this stage.