I came here to say this. I did my own benchmarks on JSON versus msgpack. I shall have to reproduce and publish them one day. If you have a lot of strings, or l

I came here to say this. I did my own benchmarks on JSON versus msgpack. I shall have to reproduce and publish them one day. If you have a lot of strings, or lots of objects where the total data in keys is similar to the total data in values, then msgpack doesn't help much. But when you have arrays of floats (which some systems at my work have a lot of), and if you want to add a simple extension to make msgpack understand e.g. JavaScript's TypedArray family, you can get some very large speedups without much work.