Fast JSON parsers are all fine and good, but take such benchmarks with a grain of salt. JSON, like any format, is useless unless you do something meaningful with it - populate a database, verify the result, or transform it in some useful way for the task at hand. Many of these faster JSON DOM-style parsing libraries store key/value pairs in lists or arrays because it's the most efficient way to do so. But they aren't great at lookup speed. If the JSON parse library is event based, i.e. SAX-style, you have to store it somewhere, and this takes CPU as well.