Emulator

If you want a performance issue looked into, the best thing to do is bisect it. If you can narrow down the range to when the issue reappeared, that'd be great. I'm pretty sure there's a build that re-enabled the instruction mentioned in the commit that originally fixed the slowdown, I'd start bisecting around that.

I will look into it, but would you have any idea of which set of revisions I should be looking in? Even if you could narrow it down into a range of 1000, it would make it easier than downloading a ridiculous amount of Dolphin revisions.

If you bisect, even with 4000 revisions you'll do something like 20ish builds to narrow it down. 4.0.2 works perfectly, so that's your good build start. 4.0-4091 is broken, so that's your bad build. So, you start off by going to midway through, 4.0-2000ish. Then, if that one is fine, you go to 4.0-3000, if it fails, you go to 4.0-1000. Then you already have a 1000 build range.

Alright then. Go ahead and leave this one open, and I'll have more info on where the problem occurs for you in the next day or two.

Just a small update; I've been investigating the issue, but unfortunately the revisions are a bit more sporadic than I anticipated. Some dolphin revisions (specifically in the 2000's) have even more problems with graphical effects, so as a result, it's become less of finding which revisions this problem does not occur on, and more of finding which revisions these problems don't occur on AND that new problems don't arise. Since this is going to be less of a small series of tests and will require me to test many more revisions, I'll get back to it this weekend.

Understandable.

Any update on this? If you haven't found the revision where this started can you tell us the range you've narrowed it down to.

I have to say that in fact official 4.0.2 also has a light stuttering on casting the heal spell (fps drops from 30 to 28), while new revisions have the problem a bit more emphasised (from 30 to 24)...now I'm trying to see if I can find the revision that caused this little slowdown

After further testing I came to the conclusion that the little slowdown or stuttering during heal spell is present in every revision (goes randomly from 2 to 6 fps), what has made it more visible (I would say hearable) is the fact that revision 4.0-879 has reduced audio latency so during the slowdown you'll also shortly hear a bit of audio crackling, but in fact emulation speed should be the same as before.
Try for yourself comparing (video & audio) 4.0-879 with 4.0-873

Is this still happening? There have been quite a few optimizations recnetly with EFB2RAM stuff. 4.0-87e had more lenient audio timings (more latency) so audio stuttering would be as bad, as you identified correctly.

I think this should be better though in latest builds, try with EFB2Texture enabled, etc.

This game doesn't need copy to RAM, so I think those changes don't affect it, anyway for me the little FPS drop is still there (4.0-5283)

Does the game itself lag, or is Dolphin lagging? Can you give me the framerate with both FPS and VPS?