I've observed that when React's profiling mode is enabled, updating the profiling fields [here](https://github.com/facebook/react/blob/1d25aa5787d4e19704c049c3cfa985d3b5190e0d/packages/react-reconciler/src/ReactProfilerTimer.js#L46) and [here](https://github.com/facebook/react/blob/1d25aa5787d4e19704c049c3cfa985d3b5190e0d/packages/react-reconciler/src/ReactProfilerTimer.js#L69-L71) during the _render_ phase seems to cause a significant deopt in [`getHostSibling`](https://github.com/facebook/react/blob/1d25aa5787d4e19704c049c3cfa985d3b5190e0d/packages/react-reconciler/src/ReactFiberCommitWork.js#L858-L898) during the _commit_ phase for Chrome only. (Neither Safari nor Firefox seem to be affected by this.)

I have created a repro case with inline annotations here:
https://github.com/bvaughn/react-profiling-v8-deopt-repro#about-this-repro-case

(Note that the above repo is private. Please tag me here if you need access.)
workInProgress.alternate = current;
    current.alternate = workInProgress;
  } else {
    workInProgress.pendingProps = pendingProps;
    
    
    workInProgress.effectTag = NoEffect;
    
    workInProgress.nextEffect = null;
    workInProgress.firstEffect = null;
    workInProgress.lastEffect = null;
    if (enableProfilerTimer) {
      
      
      
      
      workInProgress.actualDuration = 0;
      workInProgress.actualStartTime = -1;
    }
  }
  workInProgress.childExpirationTime = current.childExpirationTime;
  workInProgress.expirationTime = current.expirationTime;
  workInProgress.child = current.child;
  workInProgress.memoizedProps = current.memoizedProps;
  workInProgress.memoizedState = current.memoizedState;
  workInProgress.updateQueue = current.updateQueue;
  workInProgress.firstContextDependency = current.firstContextDependency;
  
  workInProgress.sibling = current.sibling;
  workInProgress.index = current.index;