question-it | Isomorphic Reactive Voting App - React Material-UI | Frontend Framework library

I'm trying to master dynamic forms following the official documentation but with my own case.

I have api that I'm trying to fetch data from https://demo7782009.mockable.io/form and print it out in corresponding form fields. Each field has own validation requirements.

But getting an error

Error: formGroup expects a FormGroup instance. Please pass one in.

...

My website (https://whatifhq.com) loads fine, and quite quickly. However, when I try to scroll down, it starts getting laggy and isn't smooth anymore. I've only encountered this problem in Chrome. (tested on chrome, edge, ie). I'm using Chrome V 70, WordPress for my website, and PHP 7.1

I read some other SO posts, most recommended removing some scripts, images, animations. So, I removed animate.css, Adsense, and some other images. However, it still isn't working.

This issue occurs only on the desktop. The mobile version of my site works fine on the same computer. (the mobile and desktop have basically the same content.)

One thing that may be causing the problem is my AJAX infinite scroll script. It checks what position the window is in and then decides whether to load the new content. however, this feature is also on my mobile site, which works fine. Also, the scrolling issue is also present on pages without AJAX, like this https://whatifhq.com/question/where-can-one-find-some-good-resume-cv-templates/

I've also done some speed testing and gotten really good scores. 85%+ Pagespeed, All 'A' WebPageTest.

Can someone please help?

Edit: Not Ajax. I removed the script and the page is still laggy.

Heres my My AJAX script

I'm testing a pagination type where the buttons are on a separate div from the target.

When I try to toggle the next div of the body, all of them are toggling, instead of just one.

I'm using ng-bootstrap to add some directives for my Angular 4 app. Right now I'm trying to implement a sidebar with links, which are populated dynamically. I have a group of parent links that will expand on click and show a group of other links (fragments within the page). This is what I have, based on the example found on the page: