The AWS S3 StreamWrapper implementation provides a mechanism to cache stat calls, the out-of-the-box implementation uses a simple array based LRU cache that is flushed at the end of the script. Using a more persistent cache backend might help to keep the RTT low on subsequent requests.
Current implementation: https://github.com/MaxServ/t3ext-fal_s3/blob/master/Classes/Driver/AmazonS3Driver.php#L149
The AWS S3 StreamWrapper implementation provides a mechanism to cache stat calls, the out-of-the-box implementation uses a simple array based LRU cache that is flushed at the end of the script. Using a more persistent cache backend might help to keep the RTT low on subsequent requests.