Memory issues while parsing json file in ijson

This tutorial https://www.dataquest.io/blog/python-json-tutorial/ has a 600MB file that they work with, however when I run their code

import ijson

filename = "md_traffic.json"
with open(filename, 'r') as f:
    objects = ijson.items(f, 'meta.view.columns.item')
    columns = list(objects)

I'm running into 10+ minutes of waiting for the file to be read into ijson and I'm really confused how this is supposed to be reasonable. Shouldn't there be parsing? Am I missing something?