Specifically these, as per the website (sizes as of March 21):

• Marked (5.1kb)
• Backbone (7.3kb)
• List.js (5.1kb)
• Intro.js (5.6kb)
• Platform.js (5.4kb)
• Zepto (5.1kb)
• Underscore (5.5kb)
• Dom.js (5.3kb)
• router5 (6.7kb)

Out of these, some I know do more than one thing:

• Backbone is a framework, designed to fufill many use cases with numerous features.
• Zepto is a partial drop-in jQuery replacement. It does quite a few things in its core build.
• Underscore does several things, since it's a general purpose utility belt.

Maybe, some of these should be commented out/removed?