1. A method, in an information handling system comprising one or more processors and a memory, of predicting system performance, the method comprising: identifying a Queuing Network Model (QNM) corresponding to an information technology (IT) environment that includes a plurality of servers and that perform a plurality of parallel services; transforming the QNM to a linear model by serializing the parallel services as sequential services; retrieving a plurality of hardware-based service demands; inferring a plurality of software-based service demands based on the plurality of hardware-based service demands; receiving a system transaction rate based on a user test of the IT environment; and calculating one or more predicted performance results of the IT environment based on the plurality of hardware-based service demands, the plurality of software-based service demands, and the system transaction rate.