How to stop http request from dash_renderer

I am trying a build a realtime monitoring system for high frequency data. To increase the performance, I used the extendData property of dcc.Graph() and websocket. So that, the brouser does not need to send request to get data.
I found that it still not increasing the performance as expected. The reason I found is, from the browser, I see (by inspecting network from browser) after some miliseconds browser is still sendng request and the initiator is the dash_renderer.

Mq question is:

  1. What dash_renderer do?
  2. why it is sending http request?
  3. and how to stop that?