This is a CSS performance problem I see all too often.
The React website has some jank due to their use of transition.
Here is how to find what causes it and how to fix it
Here Is How To Get The Fps Meter And A Few Other Handy Tools In Your Browsers Dev Tools
This Lando Norris Website Is Insane
How to Make a DOM Library Render Anything w/ Paolo Ricciuti
Jesus Christ 