The automatic speed test communicates with the server you have selected outside of its normal test sequence... it's testing your latency in the background.
When you're using this test, you shouldn't be surprised when my servers talk to you... it's how the test works.
If you think I'm doing anything malicious... don't use my program. You always have control over turning it on and off.
Fact is, all my code does is try to help you improve your connection. Dig apart the client-side code as much as you want... as with any good program it only does things you ask it to do.
I've been doing this for over 20 years, I respect my users and value their visiting and sharing my resources. I wouldn't do anything to jeopardize my users or the trust and reputation I've built. I wouldn't anyway, "Do unto others as you would have them do unto you."
.... it may not have done that for you in the past because you weren't a member. You have to be signed in for that feature. If you think your wireshark is going nuts now you should see what I'm building.