HP/EXP bar and screen transition lags; need help

After I defeated Nyx and leveled up my team, the game started to lag a bit whenever these three things happen and I’ve tried to speedhack the game to make it go faster, but it didn’t work. Like whenever it transitions in fading into black and out, it lags a bit. It never done this before the Nyx battle, it seems to always been faster back then.

I had to face the e4 with the HP and EXP bar going slowly, and it’s kind of a pain. I’ve restarted my computer and closed out applications and even fiddled with the two first options in F1, but no avail. Can anyone explain to me why it’s lagging? If I solve this, that means I could play the postgame without the terrible lag…