my monster gaming pc lags when emulating?

[marshedpotato]

i built a monster gaming pc that can run all newest games on ultra settings without even trying. here are the specs:

intel i7 4770k
16gb corsair vengeance 1600mhz/s
asus maximus vi hero board
gigabyte nvidea gtx 760 4gb card
corsair rm850 psu

i can run newer games on 200+ fps but when i try and play twilight princess i get about 21 and it lags really bad and it makes the music all choppy
am i doing something wrong or do i need an (even) better pc?

thanks everybody

brad