>> Its only ~500 MiB to clone a kernel git. Clients can usually decrypt this faster than the network can transit the data.
> I would expect the concern to be that the server can't
> encrypt fast enough to saturate its pipe
We actually find we have sufficient server CPU to do the SSL encryption, but there is never enough bandwidth between the client endpoint and the remote server. Our servers won't permit this experiment (they require use of SSL), but doing a git clone over http:// runs at the same bandwidth as https://, as the choke points aren't the server CPU, but instead limited bandwidth on network links between client and server.
The Google side of the network is obviously shared with other services the company offers, and this bulk data transfer traffic may be prioritized lower than other data that users want immediately, such as web search results.