Here's why:
* Slow: implies a lack of speed or a gradual pace.
* Leisurely: suggests a relaxed and unhurried pace, often associated with enjoyment.
Both words convey the idea of a pace that is not fast, but they have slightly different connotations.
Here are some antonyms for "slow" and "leisurely":
* Fast
* Rapid
* Swift
* Hasty
* Hurried