|So am I to assume that some how the usb wireless adapter is causing the whole network to slow down and speedtest to think I am in California?|
That would be my assumption. You could confirm by connecting that USB wireless adapter to another computer and testing. If the same thing happens on a different PC then it's definitely the adapter
How does this happen?
Good question. From the sounds of it, and should the same thing occur on another computer in your LAN when you attach that same USB adapter to it and try to use it, I would suspect the device is flooding your network with packets. This can happen when an adapter goes bad. (Any network interface, not just a wireless one).
If you're really curious, download Wireshark and install it on the computer with the USB adapter and then enable the adapter and let Wireshark collect data from that. Then, disable the USB wireless adapter and enable the wired adapter and do another packet capture with Wireshark. Afterwards, compare the output of the two.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.