Sudden issues in Metal Gear Solid 3

[Math-e]

So, I was playing MGS3 perfectly, until it started to slow down. It used to run at 95%~100% speed and 45~50fps (it's PAL version), and suddenly, all I get is 20~25fps ingame (menu still maintain at 50). Also, I get the following on the Playstation 2 logo when full loading the game. 
[Image: AsDEhiF.png]
Remembering I am only getting it with MGS3, and others games still run normally and neither get the glitched PS2 logo. I've tried changing some configs but no good results
Specs if you ask: Windows 8.1, PCSX2 1.2.1, i5 3330, GTX 750 Ti, 8GB RAM

[willkuer]

Possibly you use now the iGPU with broken drivers instead of your dGPU?
Possibly the iso is broken?

[refraction]

That Playstation logo is normal if your BIOS is of a different region to your game, it's not a problem.

[willkuer]

So some games are loadable using full boot and the only issue is this ps2 logo? I always thought you need to use fast boot if region of bios and game don't match.

[Blyss Sarania]

^ I thought that too.

[Math-e]

Messed a bit more with the configs and found out what was: frame skipping was on
I really don't remember how it got activated, but it was
Also didn't pay attention on what bios I was using
Thanks for the support anyways, guys!!!