Good news !  (Sort of...)

I rebooted and edited the boot command of my kernel in grub, using e... and then booted it.
I added the following to the command line:  rd.driver.blacklist=nouveau modprobe.blacklist=nouveau nvidia-drm.modeset=1

This caused the kernel to boot with nvidia instead of nouveau.   Even better, the nvidia driver decreased my CPU load tremendously in the application that I was working with.  From 90% (barely useable) to 30% (loafing along).

Now I just need to figure out what is going on with my boot setup.

Thanks for all the help!