It's pretty easy to see how much of the performance drop is protocol overhead since the numbers are there for Tokyo Cabinet / Tyrant over the memcached protocol

It's pretty easy to see how much of the performance drop is protocol overhead since the numbers are there for Tokyo Cabinet / Tyrant over the memcached protocol and not. This isn't terribly surprising. One is a distributed network protocol, the other is just moving things around in memory. The poor performance for memcachedb doesn't surprise me a lot. In my tests I've found BDB (which it uses behind the scenes) to be frustratingly slow with writes.