Various embodiments of methods of designing an integrated circuit (IC). One embodiment of one such method includes: (1) generating a functional design for the IC, (2) determining performance objectives for the IC, (3) determining an optimization target voltage for the IC, (4) determining whether the IC needs voltage scaling to achieve the performance objectives at the optimization target voltage and, if so, whether the IC is to employ static voltage scaling or adaptive voltage scaling, (5) using the optimization target voltage to synthesize a layout from the functional IC design that meets the performance objectives by employing a unitless performance/power quantifier as a metric to gauge a degree of optimization thereof and (6) performing a timing signoff of the layout at the optimization target voltage.