WebSocket ping takes a long time

I'm running a simple `for` loop in a cell. Before starting processing this `for` loop, my jupyter (either notebook or lab) fully occupy my RAM and my Disk and even I can't move my cursor. After a long time later after it, jupyter starts processing the `for` loop.

The problem is related only to the cell that consist of this `for ` loop, other cells run fast.

Here is my jupyter lab log:

```
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.
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... Adapting to protocol v5.1 for kernel ad63ee2f-6698-49d3-b2e9-2375a9084d21
... Adapting to protocol v5.1 for kernel ad63ee2f-6698-49d3-b2e9-2375a9084d21
...

*... WebSocket ping timeout after 111878 ms.

*... Starting buffering for ad63ee2f-6698-49d3-b2e9-2375a9084d21:b8ea5063-2c03-4ac2-a934-e9362df58f87
... Adapting to protocol v5.1 for kernel ad63ee2f-6698-49d3-b2e9-2375a9084d21
... Restoring connection for ad63ee2f-6698-49d3-b2e9-2375a9084d21:b8ea5063-2c03-4ac2-a934-e9362df58f87
.
.
.
```

> OS: Windows
> Anaconda: Anaconda3-5.2.0-Windows-x86_64