This report focuses on an optimization scheme of advanced MOSFETs for designing CMOS circuits with high power efficiency. For this purpose the physics-based compact model HiSIM2 is applied so that the relationship between device and circuit characteristics can be investigated properly. It is demonstrated that the short-channel effect, which is usually measured by the threshold-voltage shift relative to long-channel MOSFETs, provides a consistent measure for device-performance degradation with reduced channel length. However, performance degradations of CMOS circuits such as the power loss cannot be predicted by the threshold-voltage shift alone. Here, the subthreshold swing is identified as an additional important measure for power-efficient CMOS circuit design. The increase of the subthreshold swing is verified to become obvious when the threshold-voltage shift is larger than 0.15V.