Openshift cluster extremely slow

Issue

• Openshift cluster is extremely slow.
• slowness is generalized
  • simple navigation through the web console
  • actions
    • editing a configmap
    • accessing a pod
    • building images
• problem also occurs remotely using 'oc' command line.

• unable to run the sosreport with errors similar to

  ...
  Setting up archive ...
  Setting up plugins ...
  Running plugins. Please wait ...
  
  Running 41/92: logs...        Killed  
  

• etcd log entries

  • timed out waiting for read index response
  • the clock difference against peer <xxxxx>f is too high [6.991933922s > 1s]