At what point does it make sense to start using virtualization to render data?

Question

I'm using React to build a simple website and I often hear people say that they use virtualization to render lists of items (eg. products on a retail website). When I ask them why they use it they say that they can more efficiently render large lists.

Nobody has an answer when I ask them what "large" means and at what point a list becomes "large" enough to justify using virtualiaztion. I searched for benchmarks but couldn't find anything convincing.

Let's say someone wonders whether to use a virtualization library (eg. react-window or react-virtualized), how large does the list need to be so that it starts making sense to use such a library?