A communication stack performance of an Intelligent Electronic Device (IED) is analyzed in a communication network of a Substation Automation (SA) system. The IED processes network messages that are transferred with, or belonging to, a specific configurable SA communication service. A plurality of application level scenarios corresponding to a high communication load is executed. Among all network messages captured or intercepted during the scenario, the network messages destined to the IED and sent by the IED in response are identified. A number of the identified messages, a number of specific communication protocol elements or data items related to a service-specific property, and a number of changed protocol elements, which are indicative of an SA event, for which the value of the data item has changed compared to the value of the same data item in a previous message, are determined. An IED-intrinsic processing time of the identified messages is likewise determined, based on which parameter values of a service specific processing time model are calculated.