In a nutshell, the problem looks like this picture:

![enter image description here](https://i.stack.imgur.com/xVP5i.png)

In short, gigantic latency, very slow read speed (I assume that is caused by the same thing). After a very very painful few minutes, everything seems to go back to normal.

What the heck is going on that can cause that?

**Note:** Note the fact that 100% activity happens at a wide range of speeds.