There was a lot of attention in 2019 when the UNAI renderer was added to PCSX Rearmed, as it meaningfully improved the ability of 3DS owners to play PSX classics.
Unfortunately, as anyone who tried it out could attest, the performance was still extremely spotty. 2D games generally performed better but overall playability varied significantly from title to title.
Over the past six months, the situation has improved dramatically. Incredibly, there has been very little attention despite the huge improvements. The latest nightlies now run most PSX games at full speed, including demanding titles like Metal Gear Solid!
To get started, you will need to download a recent nightly of the PCSX Rearmed Retroarch core. Then you will need to enable the following settings.
- Compress your game to either CHD or PBP. CHD is the superior solution.
- Switch Audio Driver to DSP_Thread. This step is very important. Threaded audio was only added in the past few months and provides a meaningful performance boost. You will need to restart Retroarch to realize this setting change.
- Enable Audio Synchronization.
- Disable Video Synchronization (unless you are playing a 2D game). You will not notice a negative difference in 3D games.
- In Quick Menu -> Options, set CD Access Method to Async. You will need to restart Retroarch to realize this setting change.
- In Quick Menu -> Options, set Threaded Rendering to Async. This is extremely important. Threaded Rendering option was only added in the past few weeks.
- In Quick Menu -> Options, enable Advance GPU UNAI/PCSX4All Settings.
- In Quick Menu -> Options, Enable High-Res Downscaling. This option will only show up once you show Advanced GPU UNAI/PCSX4All Settings and then close and reopen the Quick Menu. M
For good measure you may want to Restart Retroarch after making the last changes.