title: What leverage can be used to reduce UpdateLayerTree operation in Blink?
body: <p>I'm working on web application embedded in low-end devices and i'm experiencing long <code>update layer tree</code> operations while rendering.</p>
  
  <p>I know that <code>update layer tree</code> is the operation which consist in computing or recomputing the information relatives to <code>RenderLayers</code>, usually because a top layer has been invalidated. I found this previous post which explain this pretty well : <a href="https://stackoverflow.com/questions/25724126/chrome-devtools-timeline-update-layer-tree-event">Chrome DevTools Timeline Update Layer Tree Event</a>.</p>
  
  <p>My application is built around components and each one of them might have a few layers. If i test my components separately, everything works fine and i get great performances (great fps, smooth animations). Now, when i put everything together, the performances are falling apart. What i'm seeing in chrome dev tools are long <code>UpdateLayerTree</code>. </p>
  
  <p>I was wondering what is the leverage to address this ?
  I guess the first obvious action is to try to reduce the amount of layers within the whole application. But here are my questions :</p>
  
  <ul>
  <li>Are the amount of layer the only leverage to reduce UpdateLayerTree ? (For example, does the size of a layer has any impact on this ?)</li>
  <li>Are there some tricks which triggers a quick rendering path in Blink which can avoid or reduce update layer tree operations in some particular cases (i think this is the case for inline transform ?)</li>
  <li>Do you see something else ? </li>
  </ul>
  
  <p>Regards,</p>
  
  <p>(Also, as a side note, i opened an issue in chromium project to get some feedback around this some time ago : <a href="https://bugs.chromium.org/p/chromium/issues/detail?id=725712" rel="nofollow noreferrer">https://bugs.chromium.org/p/chromium/issues/detail?id=725712</a>.)</p>