So i've been wanting to play some of my old games from the Wii, I simply obtained DKR and booted it up from Dolphin. When i got in the game, it started to lag extremely bad with Dolphin only running at 50% and FPS at 30. I tried changing graphics settings and getting 2 different ISO's. I've also tried changing them into WBFS files, nothing seems to work. My specs should be good enough. Other games such as MKW work so why shouldn't this?
Your CPU is actually pretty weak for Dolphin. Basically for AMD, anything pre-Ryzen has poor single-threaded performance, which Dolphin relies on for a considerable bulk of its performance. Your GPU only determines how high you can raise your resolution without slowing down, but that doesn't help if your CPU is the bottleneck. Also note that each game has different demands from your hardware. Some are heavier on your PC than others.
It might help of you upgrade from 5.0 to the latest development revision. It's a fair bit faster than the stable build.