Sims 2 60fps stutter

[AvarionUK]

Hi I am using the latest version of PPSSPP on my android device from Google play. I'm playing The Sims 2 and I notice whenever I move and look in certain areas I get a fixed 60fps, But in some spots it drops to 20fps. I've tried changing the settings to default and running on the lowest settings but the exact same framerate drops happen in the exact same places so that doesn't make a difference, which to me sounds like the PSP couldn't take them framerates and developers have locked variable framerates in certain spots? I don't know just assuming.
Anyway I was wondering if there was a fix for this? I have a One Plus 7 Pro and it can no doubt run this at a constant 60.