title: Apache Airflow webUI tree view is too slow
body: <p>I'm using apache airflow(v1.8.1) for workflow management. After 4-month use, the tree view page become too slow when I want to jump into a dag. The loading time for this page takes minutes. </p>
  
  <p>It looks like the tree view page is slow only for dags with a big complex tree. From chrome devtools, I can see the page is too huge(295M):</p>
  
  <p><a href="https://i.stack.imgur.com/lHtVR.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/lHtVR.jpg" alt="enter image description here"></a></p>
  
  <p>do you have any ideas?</p>