The original UMD ISO is ~1.6–1.7 GB. A “high compress” version reduces it to 400–800 MB by compressing video, audio, and sometimes removing data.
Inside the ISO structure (using UMDGen), delete the PSP_UPDATE folder. Dissidia 012 contains firmware updates for PSP version 6.39. That folder is roughly 35MB. Deleting it is safe for CFW (Custom Firmware) users. dissidia 012 final fantasy psp high compress
: Recoding high-quality cutscenes or music into lower bitrates. Performance & Requirements Version Type Recommended For Standard ISO Maximum quality, fastest native loading. CSO (Compressed) ~1.1 GB - 1.3 GB Balance between space and speed. Rip / Highly Compressed 497 MB - 600 MB Extremely limited storage (SD cards < 4GB). The original UMD ISO is ~1