GitHub now supports version 2 of the Git wire protocol. An immediate benefit of the new protocol is that it enables reference filtering on the server-side, this can reduce the number of bytes required to fulfill operations like
git fetch on large repositories. [source, source, source, …]
To utilize the new protocol, your git client must be at or beyond version 2.18, released June 2018 and the protocol version must be specified in your git client configuration:
$ git config --global protocol.version 2
For more information about the differences between version 1 and 2, please see the official git documentation on the changes.