Web is fast, web is slow. Your app should be accessible to all users, regardless if they are on a super-fast fiber network or on a 3G/2G. You can have an amazing app running super fast, but if users are not able to load it, it’s useless.
There are many studies about how page load time actually affects conversion rates. After 2014, mobile usage has taken over desktop use; since then, we've needed to focus on mobile first. And mobiles are unfortunately prone to be on a slow network.
The math here is simple. The less data there is to load, the faster the load is.
Performance plays a major role in the success of any online venture. Please follow Why Performance Matters on Google’s Web Fundamentals. Take an extra look on provided case studies. It’s obvious that when a web app is faster, it’s more successful.
https://wpostats.com/ - Case studies and experiments demonstrating the impact of web performance optimization (WPO) on user experience and business metrics.
How to improve runtime performance?
react-window - React components for efficiently rendering large lists and tabular data
WebGL for hardcode web animations accelerated by GPU