While working on the DevTools profiler, I've noticed that durations are sometimes incorrect. This seems to be vaguely related to high/low priority state updates. Need to track this down more so I'm filing an issue for myself.
workInProgress._debugID = current._debugID;
      workInProgress._debugSource = current._debugSource;
      workInProgress._debugOwner = current._debugOwner;
    }
    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 = 0;
    }
  }
  
  workInProgress.childExpirationTime = current.childExpirationTime;
  if (pendingProps !== current.pendingProps) {
    
    workInProgress.expirationTime = expirationTime;