Without looking at your GFX.ini, which contains your video backend settings, the only parameter I see that may be causing your slowdown is:
OverclockEnable = True
You have Overclock = 4.00000000, which means that you are trying to run the original Wii CPU at 4x speed. I don't know how dolphin reacts to this setting if you CPU can't keep up but it's worth checking if turning OverclockEnable = False fixes your problem.
OverclockEnable = True
You have Overclock = 4.00000000, which means that you are trying to run the original Wii CPU at 4x speed. I don't know how dolphin reacts to this setting if you CPU can't keep up but it's worth checking if turning OverclockEnable = False fixes your problem.
Windows 11 | i7-9700K | NVidia RTX 4060 Ti 8GB | 32GB DDR4-3000