Oh for crying out loud. In a lot of use cases, msgpack can be treated as a smaller, faster JSON. Let's do a quick experiment. Here's a small, very ordinary JSON document:
Using Python's json and simplejson modules, which are quite zippy, the encoding time was about 11.4 us, and the decoding time was about 8 us. With msgpack, the encoding and decoding times were 2.7 us and 1.7 us, respectively. The encoded size was 187 bytes with JSON, and 140 bytes with msgpack. Zlib compression brought those down to 127 and 125 bytes, while bringing the total encode-and-compress time up to 25 us for JSON and 16 us for msgpack.
http://graph.facebook.com/btaylor
Using Python's json and simplejson modules, which are quite zippy, the encoding time was about 11.4 us, and the decoding time was about 8 us. With msgpack, the encoding and decoding times were 2.7 us and 1.7 us, respectively. The encoded size was 187 bytes with JSON, and 140 bytes with msgpack. Zlib compression brought those down to 127 and 125 bytes, while bringing the total encode-and-compress time up to 25 us for JSON and 16 us for msgpack.