Resource ‘hogs’ – narrowing down the culprit

Hi

I have some periods of high resource usage on my site and when checking the report in CPanel…

• about 90% of CPU resources are shown as "php-fpm: pool"

• About 60% of Memory resources are from "/usr/sbin/httpd -k start"

This happens with only 5-10 people on the site at any one time, so not traffic related I don't think.

How can I (a) see what this is from and (b) see the cause specifically? (e.g. certain plugin or whatever)

Thank you.