Video - stream slow using s3 content store

Video - stream - this works.. however on larger files it is slow.. How can I improve the content s3 store to deliver the content faster ?

I have tried returning a byte array and copy to a buffer.. all load.. just slow... I am not sure where the bottle neck is coming from..

  Optional<File> f = filesRepo.findById(id);
        if (f.isPresent()) {
            InputStreamResource inputStreamResource = new InputStreamResource(contentStore.getContent(f.get()));
            HttpHeaders headers = new HttpHeaders();
            headers.setContentLength(f.get().getContentLength());
            headers.set("Content-Type", f.get().getMimeType());
            return new ResponseEntity<Object>(inputStreamResource, headers, HttpStatus.OK);
        }

also get this warning: Not all bytes were read from the S3ObjectInputStream, aborting HTTP connection. This is likely an error and may result in sub-optimal behavior. Request only the bytes you need via a ranged GET or drain the input stream after use.