From what Iβve read, heat acclimation moreso refers to the physiological changes that can make you more comfortable in the heat - more effective cooling because of a higher sweat rate, increased blood plasma volume, lowered heart rate, slower rising of core temperature. Iβm not 100% sure if this means being able to run at your normal pace/effort, but Iβm guessing that is the case! Or at least close to your normal pace/effort.