Why prefixes in S3 increase performance?

Hey. Watching this lecture https://learn.acloud.guru/course/aws-certified-solutions-architect-associate/learn/iam-s3/9db943dd-768b-47c8-98e6-283ade36836a/watch

and it says that using prefixes in S3 (/folder1/folder2 etc.) increase the performance if the bucket. I’m wondering why does it happen? Couldn’t find any information about this