If mod_ruid2 is compiled via EasyApache, mod_ruid2 is enabled, and a user has their shell set to jailshell or noshell, enabling this option will chroot() a user's Apache Virtual Host into the cPanel® jailshell environment. Each user will require 14 bind mounts. While modern Linux supports a very large number of bind mounts, many processes read /proc/mounts. Reading /proc/mounts can be quite expensive when it becomes large.
This can also create unpredictable responses to the content, such as the sites returning a 404 page.
You will want to make sure that the following feature is turned off:
EXPERIMENTAL: Jail Apache Virtual Hosts using mod_ruid2 and cPanel® jailshell.
You can confirm this is off by goto to the WHM >> Home »Server Configuration »Tweak Settings and find the setting.