Excessive cpu from physical standby database monitored by EM 12c

Added 11.2..0.2 data guard to EM 12c , but next day I always found the CPU utilization is almost 100%.
The load of uptime can be more than 20 for a two-core VM server.

Managed to check the MODULE name of active session, most of which are emagent_SQL_oracle_database and Oracle Enterprise Manager.Metric Engine.

Did quick check on metalink, found one similar case reported in 10.2.0.5. 
 Grid Control Agent Consumes High CPU when Monitoring Standby RAC Databases [ID 864829.1]

Anyone has similar experience with mine ? Hope it is not an old bug in 12.1.0.2 EM Cloud control.

As workaround, I have to remove the physical standby database from 12c Cloud control.