The answer lies in the rendering pipeline. PSP used a tiled rendering architecture (unusual for the time), where the GPU processed small screen tiles independently. Porting that to PS2’s traditional immediate-mode renderer required rewriting the lighting and culling systems. Rockstar Vienna rushed the conversion, leaving inefficient code. Digital Foundry’s 2006 analysis called it “a compromised port that fails to leverage the host hardware.”
If you are looking for a more "pure" port rather than a remake, the re3-vita/re3 project gta+3+psp+port+fixed
There is a project based on the reverse-engineered source code specifically targeting the PSP . The answer lies in the rendering pipeline
: To run on 32MB of RAM (standard for PSP-1000 units), some visual and world simplifications were necessary compared to the original PS2 game. The original homebrew port fluctuated between 15 and 25 FPS
The original homebrew port fluctuated between 15 and 25 FPS. A "fixed" version must lock at 30 FPS (or 20 FPS stable) even during explosions and rain.
If you searched for , you already know the pain. You’ve experienced the missing textures, the single-digit frame rates, and the crashes that corrupt saves. For years, the dream of playing the original gritty classic on Sony’s handheld felt like a myth.