FPS drops from 60 to 5 all of a sudden

[Miyaca]

Hey!
I'v been playing Monster Hunter Portable 3rd a while now.
My PPSSPP Version is 1.10.3.
I'm playing with two friends on the same version and until now there was no problem with the framerate so far.
All of a sudden my game started to lag. I tried to restart PPSSPP, my PC ect.
Nothing worked. I loaded in one of my Monster Hunter Freedom Unite Saves and there it would leg too.
I saw a thread with a similar problem beeing solved as the OP blocked a virus on their PC. I ran a very long safety scan and even found a trojan, got rid of it, but did not help.

I didn't changed the settings or other stuff in PPSSPP, because it worked fine for me for two years, so I don't think therein lies the problem.

Any ideas?
Hope you could understand, because english is not my fist language.
I made a new post, cause I could not finde any other threads with the same or similar problem