I am writing a web app and I want it to be as responsive as possible to the user.

When I do an ajax request with dataType:'json' it takes 10ms longer before the success handler is called than if I do dataType:'text' and then do a manual jQuery.parseJSON();

With json parsing before handler is called it takes my request 21-25ms to parse some arbitary json

With plain text fetching and manual parsing with jQuery.parseJSON its 11-16ms for the same job.

I'm just curious why this is, because in my experience choosing to receive json should be faster then an extra call manually, but its not the case.