Last time I tried streaming parsing it was with Oboe.js which wasn't bad but I remember it having approximately a 5x speed penalty. So you get your first item in your dataset faster, but the whole thing loads slower - a tradeoff that's not a no-brainer. I wonder how getline plus many repeated calls to json.parse work in comparison to that - I suspect the native parser probably has some startup overhead but still better than a JS parser.

The other thing was that to get the full benefits of something like this (not necessarily about streaming parsers vs not) you had to rearrange the way your /whole/ stack works, streaming all the way from the database through all the backend layers to the frontend. It's satisfying when it works, but definitely a non-trivial amount of change.