and with little data (i.e. <10Mb), this matters much less than accessibility and easy understanding of the data using a simple text editor or jq in the terminal + some filters.
Also good luck parsing 10 MiB of JSON in a loop that can't tolerate blocking the CPU for more than 10ms.
What's expensive is very relative to the use case.
what do you mean by little data, most communication protocols are not one off