Lab
Reading about performance metrics is one thing; feeling them is better. Small, self-contained experiments — more to come.
What does a slow INP feel like?
Interaction to Next Paint measures the time from your input to the next frame the browser actually paints. This demo blocks the main thread for a duration you choose, then measures the real gap — try 200 ms, then try 1000 ms.
2 · Click and feel the number
INP thresholds: good ≤ 200 ms · needs improvement ≤ 500 ms · poor > 500 ms. Notice the measured number is always a bit higher than the requested block — input delay and presentation time are part of the interaction too, which is exactly why INP catches problems that handler-timing alone misses.