What's different of requiring json or js?

[Kei Son]

(copied my issue from nodejs group:  https://groups.google.com/forum/?fromgroups#!topic/nodejs/adowj-PAJfo)

I have a huge JSON file, right, it's 78MB.

When I just require it from node-cli it takes 450MB memory footprint. I can understand that is bloated 6x times because the JSON file is just a string  in the storage, but it needs spaces for indexing, making some padding, optimization, linking and whatever else when it comes on memory.

But the other hand, when I add some strings like "module.exports=" at the top of the JSON file and require it as a normal js file, it takes only 200MB. I thought requiring as JSON would be faster and smaller than as JS. Because there are no seeking time for code-optimization and no extra process at the Node.js side.

What's different between two and why?