This paper proposes a streamlined method to model, analyze and assess the overall performance of small mobile machines that can move along large parts to perform the required machining operations, conventionally called portable machines. The method is based on virtualization techniques and combines a process-force mechanistic model and a reduced machine stiffness model synthesized from virtual and experimental reduced models of subsystems. The model is used to assess and improve the performance of portable machines by examining the time-domain response of the tool center point in representative operations, rather than limiting the study to the frequency domain. A practical application to a particular portable machine is presented and used to conduct the presentation of the work. With the results of the analysis, the accuracy of the use of the portable machines is studied. The procedure also proves to be a useful tool to optimize the machine design to fit particular applications. The method has been experimentally evaluated in a conventional three axis milling machine to ensure the accuracy of the simulations. (C) 2016 Elsevier Ltd. All rights reserved.