Screen turning black every particle that appears

[[Unknown]]

"Non-buffered rendering" is, in other words, "Ignore when the game tries to use buffers for effects." It prevents effects from being applied and renders faster (because there's no buffers - no copying things around), but well, it prevents effects from being applied.

The brightness you're talking about is caused by bloom. Without going into detail about how bloom works, it's an effect games intentionally apply to make things look better - and it works great. However, most PSP games (as shocking as this may be) were designed only for the resolution of the PSP device - and so when they do effects like bloom, they do them in ways that don't always work at resolutions the PSP was not capable of (that is, any resolution except 1x.) So basically, the PSP game you are playing was designed to have "graphics from Nintendo".

There's a hack in the settings that tries to detect bloom, specifically, and prevent this problem. Unfortunately, it's not always possible to detect it correctly in all games. I think the setting is called "Lower resolution for effects (reduces artifacts)". It may also cause some other parts of the game to reduce in quality (since sometimes it thinks other effects are bloom when they are not.)

-[Unknown]