I am seeing the above issue with HomeAssistant 0.72 (which had a major Arlo code update).
I constantly see logs like this:
Jun 27 03:09:44 hassbian hass[11362]: 2018-06-27 03:09:44 INFO (MainThread) [homeassistant.core] Bus:Handling <Event state_changed[L]: entity_id=alarm_control_panel.arlo1, old_state=<state alarm_control_panel.arlo1=unknown; code_format=None, changed_by=None, attribution=Data provided by arlo.netgear.com, device_id=None, friendly_name=Arlo1, icon=mdi:security @ 2018-06-26T20:06:41.099059-07:00>, new_state=<state alarm_control_panel.arlo1=unknown; code_format=None, changed_by=None, attribution=Data provided by arlo.netgear.com, device_id=4R03747YA88F6, friendly_name=Arlo1, icon=mdi:security @ 2018-06-26T20:06:41.099059-07:00>>
Jun 27 03:09:47 hassbian hass[11362]: 2018-06-27 03:09:47 INFO (MainThread) [homeassistant.core] Bus:Handling <Event state_changed[L]: entity_id=alarm_control_panel.arlo1, old_state=<state alarm_control_panel.arlo1=unknown; code_format=None, changed_by=None, attribution=Data provided by arlo.netgear.com, device_id=4R03747YA88F6, friendly_name=Arlo1, icon=mdi:security @ 2018-06-26T20:06:41.099059-07:00>, new_state=<state alarm_control_panel.arlo1=disarmed; code_format=None, changed_by=None, attribution=Data provided by arlo.netgear.com, device_id=4R03747YA88F6, friendly_name=Arlo1, icon=mdi:security @ 2018-06-26T20:09:47.889640-07:00>>
Jun 27 03:10:41 hassbian hass[11362]: 2018-06-27 03:10:41 INFO (SyncWorker_2) [homeassistant.components.arlo] Updating Arlo Hub component
Jun 27 03:10:54 hassbian hass[11362]: 2018-06-27 03:10:54 WARNING (MainThread) [homeassistant.helpers.entity] Update of alarm_control_panel.arlo1 is taking over 10 seconds
Jun 27 03:11:42 hassbian hass[11362]: 2018-06-27 03:11:42 INFO (SyncWorker_10) [homeassistant.components.arlo] Updating Arlo Hub component