Well first, we need to know which version you're emulating, since it's on 6 different consoles, 2 different PC versions and a mobile version, as well as what emulator you are using.
Then there's specs. What are they?
"NintenDON'T sue me please haha"
It started at the very first mission, when Harry is practicing quidditch with Ginny the frame drops right away lowered to 9 fps. Sometimes the fps become stable again but drop very often and it is hard to play