I did install the updated driver for my realtek gbe controller . Problem persists. . And I checked for bloatware - nothing there. I also ran through the other links you provided (thank you) and either it's not pertinent to this situation, or I've done it already.
Here's a screenshot from TM during the event with one of my simulators running - which is what is generating the bit of network traffic. You can see the GPU spiking downward at the same time the Ethernet utilization is changing. You can't see what's happening with the CPU because everything there that's pertinent is at the thread level. But I've described the spike up in several threads already.
You can see that the spike up in 'receive' starts a bit prior to the downward spike in 'send'. And that the graph shows that the initial down and up spikes lines are overlaying each other - occurring simultaneously. Meaning one is probably affecting the other or are interrelated in some way.