The antonyms of the phrase 'most fast talking', which means speaking quickly, can be 'slow-talking', 'leisurely', 'unhurried', 'calm-speaking', 'deliberate', 'thoughtful', 'measured', and 'slow-paced'. A slow-talking person speaks with a relaxed and unhurried manner, while a leisurely speaker takes their time to express themselves. An unhurried speaker speaks slowly and deliberately, while a thoughtful speaker takes time to think about what they are going to say. In contrast, a fast-talking person may come across as being impatient or trying to rush their message across. Therefore, using antonyms to describe the opposite qualities can be useful for those who wish to communicate effectively.