First thing that pops to mind is jQuery animations vs CSS transitions/keyframe animations, especially on low-powered mobile devices. I guess that's not explicitly jQuery vs JS, but it's still an example of how it can be done far better.

There's also the fact that you don't have to include a gigantic library of functions you'll never use, just to show a box when you click a button. 37kb is way over 10% of my ideal page load for a simple to moderate site.