In this study, one of the prominent and the basic analytical methods for the frequency analysis of non-linear systems, Volterra Series method is discussed. Then the computational load of the method and the symmetrization process is investigated. For this, a third-order non-linear system model has been used and the frequency response of the system has been obtained. The investigation is performed by detecting the periods of every step of the method and the symmetrization process. The obtained results are presented in tables and graphs. The factors which affect the performance of the method are identified. Finally, parallel computing of the method has been realized on 8-thread computer by using MATLAB (R) parallel processing toolbox and the results (speedup and efficiency) have been interpreted.