Performance issue of flatList in Ext JS - extjs

I am facing a issue while trying to update scroll fast in my application. Screen became blank while scrolling fast.
I have added video link.Issue Video
I was trying to make smooth render on contact list but adding 50 per conacts scroll blank space was coming.


Why components disappears and reappears while fast scrolling

Here is the link of the website after website homepage is completely loaded and then if you scroll little faster you will start seeing blank screen and after few milliseconds component appears again.

I am using react-infinite-scroll-hook - npm

I am using react-infinite-scroll-hook - npm ,while using this in filters ,it is working on All filter fine, but remain filters i am able to show infinite scrolling and it it working fine, when we scroll down ,the scroll bar is moving to top ,how can i solve this issue.
For example, I have three filters n those are 1)All 2)Request 3)Response filters
The infinite scrolling is working fine in All filter
when we scroll down also it is working
But when we scroll down in Request and response filters ,infinite scrolling is working fine ,but the issue here is when we scroll down to page ,the scroll bar is moving back to top always. If again i scroll also ,scroll bar is going back to top. But able to fetch data
Could you please help anyone ? using react-infinite-scroll-hook and function components

How to implement a vertical scroll indicator progressbar in React project

Please check the red marked area of the picture. I need to implement this thing in a React project. It's a vertical scroll timeline indicator of all posts coming from the database.

Screen flickering/janking while rendering a grid of cards in react

I have an eCommerce site where there are product cards displayed in a grid. I am using react-semantic-ui grids and cards. Even when there are few cards, ex: 5-6 If I scroll too fast the screen flickers and slows down. The components disappear and when I stop scrolling they reappear but there's a visible lag. This is even more apparent on mobiles.
The page in question is here
I tried react-window and react-virtualized they don't seem to do much and overcomplicates the whole thing. What can I do to solve this?

InfiniteContainer not working properly codenameone

I am using an infiniteContainer in codenameone but it doesn't seem to be working properly. When I load components onto the infinitecontainer for the first time it freezes and can't seem to scroll for more components to be displayed. The container also sometimes adds the endmarker half way when creating a component. Have been finding a workaround for months and it is really frustrating.