[jesterpm]

That comparison would depend heavily on what you're storing.

Ion has the option of using symbol tables to replace strings (e.g. in struct/map keys or in values). So, if you benchmark had a large number of records with similar structures, I would expect Ion to pull ahead. On the other hand, if each record had nothing in common, I'd expect them to perform similarly.

One feature of the Ion libraries that I've liked is the parser will take any of the formats and figure out what to do with it (text, binary, compressed binary). It's one less thing to worry about. You can switch encodings later without breaking consumers, you can write plain text Ion when you're testing, etc.

[plq]

Symbol tables, compression, etc seem one level of abstraction above what msgpack provides. Such features could be implemented on top of vanilla msgpack as long as all parties agree on the msgpack schema.