iptables-restore high cpu usage in OpenShift

Issue

OpenShift nodes have a very high load average and top output reports the iptables-restore process is using most CPU. For example:

# top
   PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+ COMMAND
 99226 root      20   0   62180  18080    976 R 100.0  0.0   0:05.58 iptables-restor
121061 root      20   0 6014480 520156  38272 S  41.5  0.1  18136:02 openshift
103066 root      20   0 38.003g 1.948g  17444 S  19.8  0.4  14173:02 dockerd-current
 89157 root      20   0 2674184  58408   3480 S  15.2  0.0   3435:29 rhel-push-plugi
 ...