We consider some methods of evaluating parallel performance on clusters and MPP platforms. These methods are based on using a parallel code for the numerical simulation of 3D incompressible viscous flow in a cylindrical domain. Details of the efficient parallelization of this code are discussed for distributed memory computers with relatively slow communication links. Results of measurements of parallel performance are presented for several computers of different architectures, with the number of processors used from 1 to 16. Additionally, direct measurements of basic performance indicators are considered, such as serial performance and speed of interprocessor communications. Finally, the comparative performance analysis is presented for these two sorts of measurements.