An image forming apparatus executes a print job at an initial processing speed and switching the initial processing speed to a delayed processing speed lower than the initial processing speed upon detecting occurrence of a specific condition under which continuing the print job at the initial processing speed is determined not possible. The image forming apparatus acquires a print job targeted to be executed; estimates a processing time to be taken to complete the target print job at each of a plurality of processing speeds selected as candidates for the initial processing speed; and determines, as the initial processing speed, one of the candidate processing speeds that corresponds to the shortest processing time among the processing times estimated by the estimator.