I believe I just need to upgrade my video card and I'm considering an Nvidia 3060 TI. That will make the problem worse, not better. nVidia's driver overhead has crept up over the years. A now-ancient ...

I don't think that is an accurate summary of my advice. What I said is that you're not spending nearly enough to care about PCIe bandwidth. Unless you're going to buy a few 1080s or Titans and split ...