The performance of a mechanical stirrer is numerically investigated, when its rotation axis is moved parallel to the three Cartesian axes in the reverberation chamber. We present results for the same stirrer, and for a stirrer with the same paddles but a different length to match the chamber sides. The number of uncorrelated stirrer positions is calculated using our finite-difference time-domain code, optimized for reverberation chamber simulations in high-performance computers. No significant differences were found in the simulation results when the stirrer axis and length are changed. However, a significant stirrer performance enhancement occurs when the blade width is increased