Transfer from S3 to EC2 is fast, if they are in the same region.
If you still want faster (and reliable) delivery of files, consider keeping files pre-zipped on S3 and serve from S3 directly rather than going through your server. You can use signed URL scheme here, so that the bucket need not be public.
Next level is speed up is by keeping the S3 behind Cloudfront as an origin server. Here the files are cached in locations near your users. Serving Private Content through CloudFront