First Byte Time “FBT” findings and research results

[pmeenan]

Depends on what the proxy overhead to the origin is. If the edge nodes are essentially in the network path (not taking the traffic significantly out of the way) then at worst it is a no-op (if a new connection is established from the edge back to the origin).

Client <-> edge <-------> origin

It's not uncommon for it to look more like:

Client <-> client-edge <-------> origin-edge <-> origin

Where the CDN routes the request most of the way through an already warm and established connection and it comes out close to the origin.

The reality is a lot more complicated but it also depends on how efficiently the CDN is operating.

As far as SPDY and nginx goes, I don't think nginx implemented priorities in the SPDY implementation which was a performance killer. Instead of returning the most important resources first it would just shove them all down the pipe. Hopefully the HTTP/2 implementations behave better. I do know that the H2O proxy "does the right thing" with priorities.