That's cool, but not nuts about JSON. They should include at least one space-efficient format, like messagepack (which is 100% compatible with JSON after encoding / decoding). Of course, this opens the floodgates... Also, is zlib available?
In recent benchmarks, Node's JSON implementation is almost twice as fast as messagepack. I think I'd rather have the more universally used format anyway.
It's not about speed, but space efficiency, msgpack is significantly smaller. That's useful for a mostly in memory database. As far as speed that's negligible.