Interaction herky jerky after adding hide/show


I create a sub navigation on my photo portfolio site for a series that has several iterations. Here is the page in question:

Each of the links in the sub nav scroll to a set of lightbox links on the same page. If the user chooses to close the sub-navigation to see more of the thumbnails on the page, the links in the area that was underneath that div were not clickable until I added a hide/show to the end of the interaction. Here’s a video demonstration:
I added the hide/show and it resolves the problem but makes the animation herky jerky. Any thoughts on a better way to do this? Thanks for your help in advance.

Here is my public share link:
(how to access public share link)

Ok - I figured out what I was doing wrong with the hide/show and now the clickable issue is good but the animation is just not smooth. Any help is much appreciated. THANKS

Ok fixed this one too, but I have a new one. Adding elsewhere. THANKS