I don’t think there’s anything related to decrypting mentioned in that webpage. Do you know where can I get the IRD file ?

It’s playable. Not at very good state though.

I didn’t. I just extracted the ISO like any archive.

Can you provide any good guide for decrypting ROMs, please?

Yes. On RPCS3

It’s not at very good state though, just playable.

I am talking about PS3 one, the original. Not PS4 Remaster

I tried all of that. In EU it increases performance. But US not works.