There is a known problem that happens occasionally with Windows machines that have an ANT+ dongle which causes pretty extreme performance problems. It usually clears up if you remove the dongle, restart, and plug it back in.
Since the SB20 supports Bluetooth you could also try it without the ANT+ dongle, pair via Bluetooth, and see if performance differs. I can also test mine with an SB20 since my wife uses one. I haven’t been using ANT+ for a while since I switched to using virtual shifting.
Screen freezing usually isn’t a network problem, but poor load times and screen freezing could be related to the CPU being excessively busy, and I think that’s a symptom of the ANT+ problem I mentioned above.
Using the 4-port USB hub could also cause issues, depending on the details of the hub and what it’s plugged into, like is it a powered hub or getting power via USB, and is it USB 3 or USB 2. USB 3 is a known interference generator, and USB 2 has pretty limited bandwidth.