As you perhaps fail to understand, is quantum physics absolutely not basic science, and very hard to understand. It would take me months if not longer to grasp the basics.
So I ask people who do know how quantum mechanics works, they give arguments why virtual particles can not significantly slow photons down.
Why don't you respond to these arguments?
One was that if light is really being slowed down by virtual particles popping in and out of existance, there would have to be sooo many particle pairs that we should be able to see them.
We don't.
I'll have a look at the sources you gave and see if I have the time to investigate them.