This study presents the thermal performance of laterally perforated plate-fin heat sinks (LAP-PFHSs) with different numbers (Np) and diameters (Dp) of circular perforations. Based on the same plate fin dimension, the available diameter of circular perforations is limited by their number. The largest diameters of perforation for Np = 14, 27 and 75 are 10 mm, 7 mm and 4 mm, respectively. The computational results of solid fin heat sinks (SFHSs) and LAP-PFHSs are validated with the measured data and experimental data from the available literature. The comparison results of LAP-PFHSs give the mean absolute error of about 3.6% and 5.3% for the pressure drop and thermal resistance, respectively. According to the numerical results, the LAP-PFHS with Dp = 3 mm and Np = 75 exhibits the highest heat transfer rate, about 11.6% higher than that of the SFHS. Finally, the thermal performance factor, which is a consideration of the Nusselt number and friction factor, is proposed to find the suitable design parameters. Under the same conditions, the optimized LAP-PFHS demonstrates 10.6% greater thermal performance and 28% lower volume of heat sink material than SFHS.