Mobile View Scrolling Issue with Choppy Animation

Hey SquareSpace team,

I'm encountering a frustrating problem with my 2 websites' mobile view. Specifically, when I navigate to one of the subpages on my both sites using my smartphone, the scrolling feels incredibly choppy and jerky. It's as if there's some sort of unintended parallax effect going on.

I've implemented custom CSS to enlarge gallery images upon hover, but I've made sure to include code for a minimum media screen of 1000px, so theoretically, this shouldn't affect the mobile view. Can anyone offer insights into what might be causing this issue?

Could you check in on your phone and let me know?

Here are the link to both site: 

1. https://needlesandleaves.net/blog/2018/7/16/needles-and-leaves-two-point-0

2. https://sigmaxdownload.com/