Does MultiJson introduce slowness?

I could be using the library incorrectly, but doing a very basic test, I see results that aren't really that great. 

I've got a test and results in the following Gist:
https://gist.github.com/AaronRustad/d6f20229b9f19f6d163e

If I'm doing something incorrectly that is causing these numbers to appear worse than they should, please let me know.

Thanks!