"We recently rolled out support for protocol version 2 at Google and have seen a performance improvement of 3x for no-op fetches of a single branch on repositories containing 500k references. Protocol v2 has also enabled a reduction of 8x of the overhead bytes (non-packfile) sent from googlesource.com servers. A majority of this improvement is due to filtering references advertised by the server to the refs the client has expressed interest in."
