ARMSX2 2.9 turns one with a VU1 ahead-of-time compiler, its own GPU drivers in setup and big Retroid Pocket Duo gains

ARMSX2, the open-source PS2 emulator for ARM devices, turned one on October 26, and the team marked it with version 2.9. The first build came out on October 26, 2025. A year on, this is one of its biggest updates: two new ways to spread the PS2's work across a phone's CPU, an auto-tuner, and GPU drivers built by the ARMSX2 team that you can install from the first-run setup.

A VU1 compiler that remembers

The PS2's VU1 vector unit does most of a game's 3D math, and it's often what holds 3D-heavy games back on Android. ARMSX2 2.9 watches which VU1 programs a game runs most, recompiles them into faster code on a background thread, and saves that plan, so the next time you boot the game they're fast from the start. It's on by default as "VU1 Ahead-of-Time Compiler" under Performance settings (Advanced Speedhacks) and in the in-game Performance menu. Turning it off also deletes what it saved, which is a handy reset if a game misbehaves. General VU code is shorter and quicker too.

The IOP gets its own thread

The PS2's I/O processor handles sound, controllers, memory cards and the disc. In 2.9 it can run on its own thread instead of sharing the main emulation thread. It's a toggle ("IOP Thread", plus an "IOP Thread Lag Bound" that limits how far it can fall behind), it needs four performance cores, and it stays off for PS1 and arcade games. The game database already turns it on for Shadow of the Colossus, God of War and God of War II. On the Retroid Pocket Duo that's worth up to 11% in Shadow of the Colossus and about 6% in God of War II.

Automatic Performance Tuning

If you'd rather not dig through settings, the new auto-tuner works out what's holding a game back and tries the settings that can help: resolution, blending, texture download mode, the GS back thread and the emulated CPU clock. It only keeps a change if the game actually got faster, and it remembers the result per game. Each game's Performance page lists what it changed, with a Reset button, and changing one of those settings yourself turns tuning off for that game. It's off by default; setup asks if you want it.

ARMSX2's own drivers, and the Retroid Pocket Duo

• The Adreno 722 gets the rendering rules it needs under Turnip.
• Shadow of the Colossus now counts its shadows at native resolution, which cuts about 15 ms from a 37 ms frame at 2x, so it holds a steady 30 fps.
• Sideways-mounted screens like the Duo's top screen and the RG 55G1's portrait panel get the picture pre-rotated, so Android doesn't spend GPU time turning every frame. ARMSX2 measured that at 16 to 17% of the RG 55G1's GPU.

Everything else

• Faster: the GS back thread now gets the fastest core to itself (on by default for Spider-Man 3, Sly 3 and Ratchet & Clank: Up Your Arsenal, 1 to 24% faster on tested devices), affinity modes rank cores the way the kernel does, and both renderers do less work per frame.
• Handheld quality of life: the in-game menu reopens on the tab and option you last used, "All controllers play as Player 1" lets a docked handheld's built-in controls and a Bluetooth pad share Player 1, and volume and mute are in the quick menu.
• Recording-compatible audio: lets Android's screen recorder capture game sound on devices like the AYN Odin 3. It's off by default because it adds a little latency.
• Fixes: Tomb Raider: Legend renders correctly, memory card creation won't overwrite an existing card, .gz games show serials and covers, and the animated library background works on Mali.
• Platforms: Linux builds now ship alongside Android stables. iOS, Mac and Windows come through nightlies, and iOS also has its own stable releases.

Getting it

Grab 2.9 from the ARMSX2 GitHub releases or the official channels on armsx2.net. You need a BIOS dumped from your own PS2 and your own game discs. Overclocked doesn't link either. Not sure whether ARMSX2 or NetherSX2 suits your device better? Our ARMSX2 vs NetherSX2 guide compares them, and the emulators hub has the latest version.

Sources: ARMSX2 2.9 release notes on GitHub, ARMSX2 official site. Facts verified against the original reports; written by Overclocked.