When this cookdown criteriais found to be yellow , this means that in a workflow that contains a performance-critical module (Powershell, WMI or Script Executer), one of the modules up to and including the performance critical module may be breaking cookdown. This module is targeting a non-key property on a class that will have multiple instances on a single agent-managed machine. The class has non-key properties defined; non-key properties, by definition, are not identifiers of an instance of a class. As such, non-key properties may or may not be different for each instance of the class.
When a module is targeting a non-key property, it is picking up an instance-specific property from the object that the workflow targets. Depending on the actual values of this property per instance, and whether or not they actually differ on a per-instance basis, the module may or may not be cooked down. In such a case, it must be determined whether the property value is different per instance to determine if cookdown would be beneficial to the performance of this workflow.