Performance out of S3 is generally really good. However, if you're looking to say, serve up a global website and your content is in a single S3 region, then you

Performance out of S3 is generally really good. However, if you're looking to say, serve up a global website and your content is in a single S3 region, then you can leverage CloudFront CDN to serve up those objects. CloudFront integrates seamlessly with S3, and you don't pay transfer charges between CloudFront and S3.