Command lines on the Virtual Appliance are done through the SSH interface.
Some machines exhibit sluggishness with certain commands. Specifically, those involved with rsyslogd.
Virtual Appliance 14.0 and above
The issue is usually the rsyslogd which is forwarding its logs to a remote location.
When this forwarding is either reduced or cut back completely the performance will pick up.
Go over the file "/etc/rsyslog.d/rsyslog-custom.conf" and make relevant modifications and restart the rsyslogd daemon.