Thanks for the update. I’m similarly trying to get Mario Kart to play smoothly. Your hardware post is very useful to me.
Can I ask what OS you’re using on your new system, and is the version of Dolphin?
I'm using Ubuntu 20.04 desktop edition. I use installed Dolphin using the PPA:
https://launchpad.net/~dolphin-emu/+archive/ubuntu/ppa
After a recent bios upgrade I could also easily get the memory speed at a higher clock rate using the provided XMP profiles. I have also installed the xanmod kernel (
https://xanmod.org/), which feels a bit smoother. But even before these two adjustments I was able to play smoothly.
What is your exact system configuration (hardware/software), and how many fps do you get?