// React Profiler looks fast. Why is the page still slow?
// Teaching excerpts; see the explanation and boundaries on the episode page.

// Measure the React subtree.
const report = (id, phase, ms) =>
  console.log(id, phase, ms);

<Profiler id="Grid" onRender={report}>
  <Grid />
</Profiler>

// Mark the handler separately.
performance.mark("calc:start");
calculate();
performance.mark("calc:end");
performance.measure("calc",
  "calc:start", "calc:end"
);