Also, for those saying that TLS is a panacea: encrypting and/or HMAC'ing all TCP data in and out of a box is operationally ridiculous unless you're in some sort of ultra high security environment.
Sorry, what's ridiculous about it? It's a very achievable thing. On modern CPUs with instruction support, AES encryption can be done faster than DRAM bandwidth. There are definitely latency costs in connection setup that will penalize "transaction-like" protocols I guess. It's not 100% free, but relative to the other performance issues you're looking at it's surely way way way down the list of priorities.
Also, for those saying that TLS is a panacea: encrypting and/or HMAC'ing all TCP data in and out of a box is operationally ridiculous unless you're in some sort of ultra high security environment.