[LaurentVB]

Not sure, isn't the whole point of pipelining to avoid these domain-sharding workarounds?

This test case shows that the performance is better with the same code. The invert test case would show that the code is more complex (because of sharding) for the same performance (actually not quite, because of multiple handshakes).

[Kudos]

The whole point of pipelining is to avoid expensive TCP operations. Domain-sharding is effectively a workaround for the workaround (limiting connections to hosts).

You can actually do both domain-sharding and still use only a single TCP connection. SPDY/HTTP2 will reuse existing connections if they receive the same cert/ip combo. It's the best of both worlds while http1 still has some marketshare.