Virtual servers are not known to have a ton of memory, and when you install something like cPanel/WHM on the server you now have many services running all wanting to use that limited memory. Below is a list of things that can be done to help optimize your virtual server.
This section contains everything discussed in this article, beware as it may disable things your customers are using. For the most part it should be ok for most to run and anything it does can easily be fixed.
service xfs stop chkconfig --level 2345 xfs off service iscsi stop chkconfig --level 2345 iscsi off service iscsid stop chkconfig --level 2345 iscsid off touch /etc/cpdavddisable /usr/local/cpanel/etc/init/stopcpdavd
XFS is a X font server.
service xfs stop chkconfig --level 2345 xfs off
Used to mount remote ISCSI targets
service iscsi stop chkconfig --level 2345 iscsi off service iscsid stop chkconfig --level 2345 iscsid off
cPanel offers a webdav service, people very rarely use this
touch /etc/cpdavddisable /usr/local/cpanel/etc/init/stopcpdavd