Lazy JSON skimmer-parser. Ideal for cases where a small part of a large JSON document is accessed. Super-low memory footprint. Speed depends partly on the structure of the document and the offset of the portion of interest.
In your Gemfile:
gem 'lazy-json'
require 'lazy-json'
# Attach to document. Zero up-front processing here.
lj = LazyJson.attach(json_str)
# Skim to the value of interest and parse
lj['users'][10627811]['stats']['one_week']['message_count'].parse