Yeah... that's about it. The issue is it causes browsers low-end or even medium-end devices, especially mobile devices, to lag or even completely freeze when trying to load core-js' GitHub repository homepage, or anywhere else that embeds core-js' README, which is a terrible accessibility problem. (and also a little ironic in how a library geared towards supporting old systems fails to do so with the most basic thing like a README)

For a reference benchmark, the current core-js GitHub homepage (https://github.com/zloirock/core-js) will completely freeze my browser for roughly a full minute before the README is fully loaded in, with my specs listed below:

• OS: Android 11 aarch64
• CPU: Qualcomm ATOLL-AB (8) @ 1.804GHz
• RAM: 6GB
• Browser¹: Opera 67, Firefox 97, Chrome 98
  ¹: Tested in multiple browsers to ensure it isn't a browser-specific issue, although timings were not consistent (Opera freezes for a full minute, Firefox for around 20s, Chrome for around 10s but keeps stuttering upon scrolling), they all froze for some period of time nonetheless.

As you can see my system a quite decent medium-end system, so I can only fear for those on the lower end. I urge you to consider matching the GitHub README to the npm README, short, concise, and performant. The remaining information on the current README (the documentation part, which is 90% of it) should be split up into multiple smaller .md files properly organized in a folder structure inside the /docs/ folder which already exists on the repository, and only being used for the core-js@3 announcement, which can coexist with the additions. This would make the docs modular and easier to navigate aswell, so it's a win-win even for those on high-end systems that would never notice this to be a problem. Just imagine if MDN decided to put all their docs into a single monolithic markdown file... even if your PC could handle loading it, it would still suck to traverse.