PS3 emulation just got 60 percent faster on ARM, and it started with one busy-wait bug
Six months of ARM64 work in RPCS3 lands 60 percent more performance at 25 percent less power. One timer bug was worth a quarter of it on its own.
RPCS3 developer whatcookie has published six months of ARM64 optimisation work, and the headline number is worth reading twice. “Today, we’re able to emulate the PlayStation 3 60 percent faster while drawing 25 percent less power.” Faster and cooler at the same time is not how performance work usually goes. It is how performance work goes when the code was doing something genuinely wrong.
The something wrong is my favourite kind of bug. RPCS3 uses a busy wait, a loop that spins in place while it waits for a moment to arrive, and on ARM that function was running roughly 150 times slower than on x86, measured on an AYN Odin 2. The fix was to scale the time spent waiting by the frequency of the timer, because ARM and x86 do not tick at the same rate and the code had assumed they did. That single change was worth about 25 percent average performance and around 10 percent power on its own. The rest came from ARM-specific code paths in the layer that translates the PS3’s Cell processor instructions, where operations that were being emulated the long way round now compile into shorter native sequences. RPCS3 says one ARM64 change alone fixes several hundred games, including the Ratchet and Clank series.
How the work got done is almost as good as the result. Whatcookie describes going through more than 17,000 pages of ARM architecture documentation, and buying an Odin 2 and installing Linux on it because that was the cheapest ARM machine that would do the job. Six months, one handheld and a stack of manuals.
POCG covered RPCS3 in July, when the project crossed 75 percent of the PS3 library rated playable on PC, 2,681 games out of 3,559, a few weeks after Sony confirmed it will close the PS3 and Vita stores by July 2027. That story was about whether the games run at all. This one is about where they run, and those two questions are converging on the same answer, which is a handheld you can buy today rather than a tower under a desk.
Now the part I want to be careful about, because this is the sentence that gets lost every time an emulator posts a big number. Sixty percent faster than slow is still not fast. The reference device here is an Odin 2, a Snapdragon 8 Gen 2 class handheld well up the price range, and even on that hardware PS3 emulation remains selective rather than universal. A $60 Anbernic is not about to run Demon’s Souls. What has actually changed is that the machines where PS3 emulation is plausible got meaningfully cheaper and meaningfully more portable this week, and that the gains apply across ARM on Linux, macOS and Windows rather than to one device.
Sony is switching off the store that sells these games in eleven months. Volunteer developers reading 17,000 pages of chip documentation are the reason they will still be playable afterwards. That is the whole preservation argument in one story.