When should I report an issue?

[[Unknown]]

I would say if a game becomes unplayably slow on reasonably modern hardware with default settings, it's a bug that should be reported on GitHub. If it's just slow on old hardware, or just slow with settings like Texture Scaling or Render Resolution cranked up, then I'd suggest it's not necessarily a bug that anyone can do anything useful about.

That being said, the slow effects are the effects that are hard to emulate - not necessarily that are more amazing.

The PSP allowed games to "peek behind the curtain" if you will, and monkey with the guts of rendering. Modern graphics cards are so advanced, they can't allow this - but the ways you can do things "the right way" are all amazing and fast. Unfortunately, when a PSP game does it "the wrong way" it's like looking at some woodshop project where the builder really didn't think through how cabinet doors require space to swing open. Translating that to "the right way" usually means "slow".

But maybe we can look at this game's crazy cabinet and understand what insanity they were trying to do, and translate it better.

-[Unknown]