[raimue]

You should be aware that even for asymmetric encryption, only a one-time document-specific key will be encrypted with the asymmetric algorithm. The document itself will always be encrypted using a symmetric cipher.

This is how the same document can be encrypted for multiple recipients efficiently, without duplication all the data. First the document is encrypted with a symmetric key, which is then encrypted with the public key of each recipient. This information will be prepended to the actual encrypted document.

For details see: https://tools.ietf.org/html/rfc4880#section-2.1