I realize http is extremely well known and documented so it's relatively easy for backend communications but I've always wondered how efficient it actually is considering how old the standard is.
It's actually fairly good now that most of the improvements in 1.1 can be used with browser support like pipelining, compression, keep-alives and so on. However it isn't perfect SPDY is better still as it allows for things like muxing and pre-emptive resource downloading.
