Emulation became possible by running Linux on PS5 and installing RPCS3, the most advanced PlayStation 3 emulator. This allowed assessing the performance of classic games on modern hardware.
Some projects showed excellent results. Ridge Racer 7 managed to run in 4K and 60 FPS, Heavenly Sword even worked in 5K with stable performance higher than the original PS3, and MotorStorm received a noticeable improvement in image quality after resolution upscaling.
Killzone 3 performed particularly well. After disabling one of the post-processing effects, the game was able to maintain almost stable 4K and 30 FPS, which is already being called potential proof of the possibility of bringing PS3 classics back to new platforms.
However, not all games run stably. GTA 4, Metal Gear Solid 4, and God of War Ascension heavily load the processor and SPU blocks, causing performance to drop below the level of the original console.
According to Digital Foundry, the main problem is the PS5's Zen 2-based CPU, which may not be powerful enough for ideal emulation of the most demanding PS3 games. As a result, full compatibility may only be possible on the next generation of consoles.
Despite this, the experiment showed the main thing: PS3 emulation on PS5 is possible, and a number of games already run significantly better than expected.