If you are in a shell session and have to choose between executing python -c or calling jo, the latter is faster as you’ve demonstrated. But that’s not a realistic assumption.

Statements like these are almost certainly part of some combined work. The data you’re feeding to jo comes from somewhere. Its output is written somewhere.

You can’t convince me that if you’re already inside some Python script, that invoking json.dumps() is slower than calling jo from within a shell script.

At no point did I claim that launching Python AND running that json.dumps() is faster than running that shell command. I only stated that the json.dumps() is.