A user with the permission to view the performance tab of a VM gets the following error when switching to the real-time view:
„General report generation exception“
The user has no problems to view the data charts for eg. „past day“ or „past week“.
According to KB 2123566 „Cannot view advanced performance data charts in VMware vCenter Server 6.0“ you have to grant the user read-only permissions on the vCenter level to view the real-time performance charts, as the data is pulled from there.
This would allow the user to see the whole infrastructure.
Therefore you should take care not to propagate the permission to any child objects when setting this permission:
In this way, the user can view the realtime performance charts without having read-only access to the whole infrastructure.