Hiding and revealing toggle responds very slow
All this adding/removing classes are too much for this functionality. This makes it also very slow.

You can iterate over all div elements, and say if div is !== hidden, than hide it. 

After that, you get the clicked element with $(this), and just say

$(this).next().slideToggle();


This is not proper code, but since you don't have thousands of divs to iterate over, just hide every open div, and open the clicked one.

Maybe you have the problem of you want to close the already open one, so just make two if's. The first one should be like:


  if($(this).next().style.visible === "true"), hide it, if not, hide
  every visbile div and make just the next to the clicked one visible.


This should be much faster, because you don't add/remove/readd classes.