title: Large "idle" bars in Chrome dev tools Frames Timeline
body: <p>I'm drawing some shapes (arc, lineTo, etc.) to a  using <code>requestAnimationFrame</code>. Nothing too fancy, but I'm noticing some occasional jerky animation. I profiled using the Timeline inspector in Chrome dev tools, and am seeing a large amount of idle time per frame, some of which drops the FPS below 60 (see screenshot). Is there a known cause or resolution for this?</p>
  
  <p><img src="https://i.stack.imgur.com/LM80A.png" alt="frames with lots of idle time"></p>