If you experience a black screen, change your Rendering Mode in the PPSSPP settings from "Buffered Rendering" to "Skip Buffer Effects" to boost speed.
Wait, the user's example review mentions "optimized for gameplay fidelity" and "minimal impact on performance." I should check if that's accurate. If the file is highly compressed without too much quality loss, that's a key point. Also, maybe include a note about legal issues since PS2 games aren't typically released for PSP. But since the user is focusing on the file itself, perhaps just mention that it's for enthusiasts and legal considerations apply.
Additionally, downloading copyrighted ISOs (even “highly compressed”) is , which is illegal in most countries.