Comment by dathinab

I think on important thing to realize is that using CBOR or MessagePack does not involve compression (except if you add it in the same way you do for JSON as another layer).

CBOR and MessagePack are more compact but they do not archive this by compression but instead by adding less noise in-between your data when placing your data on the wire.

E.g. Instead of (in JSON) outputting a " then going through every utf-8 code point and checking if they need escaping and escaping it and then placing another " They place some type tag +length hint and then just memcopy the utf-8 to the wire (assuming they can rely on the input being valid utf-8).

The only thing which goes a bit in the direction of compression is that you can encode a integer as tiny, short or long field. But then that is still way faster then converting it to it's decimal us-ascii representation...

Through that doesn't mean they are guaranteed to always be faster. There are some heavy absurdly optimized JSON libraries using all kind of trickery like SIMD and many "straight forward" implementations of CBOR and MessagePack.

Similar you data might already be in JSON in which case cross encoding it is likely to outweigh and gains.