Popularized by React Fiber demo.
Run it here
This demo is often misunderstood. Even I didn't really get it 100% at first. It's not about the FPS since on most computers these days can run at 60fps. It's about how they degrade under low CPU resources. I previously suggested throttling the CPU in chrome dev tools, and that's still a good exercise but this isn't just about external aspects. React purposefully sticks a slowdown in the component to simulate an expensive computation in every single node. I've done the same with Solid now.