There are two things I can think of - It could be the game you're playing (Please note the games you are finding this issue on, that'd help)
And CPU speed - I could be wrong but I think lowering the CPU speed in Dolphin lowers speed in general. Check to see what it is and make sure to put it on the default.
"NintenDON'T sue me please haha"
When I am playing certain games in certain areas the speed of the emulation drops to about half. Specifically hyrule field in twilight princess. I have what I thought to be a fairly decent pc I am running a ryzen 5 5600 cpu with an nvidia 1650 gpu with 32gb ram ddr4. I have tried messing with all the graphics settings watching YouTube videos to see if it helps and so far it hasn’t matter if it’s top notch or bottom of the barrel graphics, it seems to still keep me at half speed in certain areas. Is there something I am missing that will help me keep the game running at normal speed?