Spawn's stutters still there in latest dev releases

EDIT: this problem disappears when using old versions of the emulator, the issue is between AMD graphics drivers and latest builds.

Like the title says, framerate problems in Spawn are still there in the latest dev releases.

I already posted about this last year: basically, the game goes nuts from level 5 and becomes unplayable for unknown reasons (no glitches, graphics/sound bugs etc). I've tried various disc images and game versions (PAL, JAP etc) and I'm using a GDI US image that's basically flawless for half an hour or so. I also tried switching AMD drivers but the problem's still there.

It's probably linked to my old PC's specs, but it's also quite odd since 99% of other games work fine on the same machine.