At least it cleaned up the log file a bit.
Citra only utilizes 1 core for running the game itself (a limitation carried over from the 3DS). It also has to translate one structure set into another, so the emulation isn’t perfect. Expecting it to fully saturate your CPU is impossible. However, I don’t think you should be experiencing that much performance reduction. Please try updating your GPU drivers: https://www.nvidia.com/Download/driverResults.aspx/168778/en-us
Also go to
File>Open Citra Folder, then open up the config folder and delete the
qt-config.ini file found there. Now restart Citra.
If that doesn’t yield any results, you can try underclocking in Citra to around 50% to see if that improves performance (keep in mind that this may increase instabilities).