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

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.