Antonyms for the phrase "makes short work of" would include phrases such as "struggles with," "takes a long time to accomplish," or "encounters difficulties with." These phrases imply that the task at hand is not easy to complete and may be tedious or challenging. Conversely, the phrase "makes short work of" suggests that the person or thing being discussed is efficient and skilled, able to complete a task quickly and with ease. By contrast, the antonyms of this phrase imply a lack of skill or resources, or a significant obstacle to overcome in order to achieve success.