New Cemu emulator hack enables 60 fps in The Legend of Zelda: Breath of the Wild

Stage one of the dream: being able to play The Legend of Zelda: Breath of the Wild on a PC. Stage two of the dream: being able to play The Legend of Zelda: Breath of the Wild on a PC, at 4K. Stage three of the dream: you probably know where this is going. Breath of the Wild, on PC, at both a higher resolution and a higher framerate than it can manage on its original hardware. The Wii U and Switch may be locked to 30 frames per second, but in the land of 60 fps, that was never going to last. And it looks like we've now taken a big step towards stage three, as a modder has done the preliminary work to make Breath of the Wild run at 60 fps on PC.

The work comes from Cemu emulator community member Xalphenos, whose post in the Cemu Discord channel was copied over into its own Reddit thread. It's a good news/bad news situation. The good news is that a fairly simple hack appears to bypass Breath of the Wild's 30 fps lock without causing any messy conflicts. The bad news is that this isn't a magical elixir that improves the game's performance, and the Cemu emulator and Zelda are currently so demanding, no system can really run BotW at a full 60 fps.

"If you get 30 now you will get half speed 30 with this 'mod.' At the moment this is really only valid for use in shrines since physics are now set to be full speed at 60 fps," Xalphenos' post begins. "This pack should really just be considered a proof of concept. It was only a hasty altering of one line of code so that I could get a few other eyes on it and make sure I wasn’t convincing myself of something that wasn’t real…"

To be clear, the hack doesn't only apply to shrines, but those areas tend to perform much better than Zelda's overworld, which is vastly more complex. The post continues:

"To answer two quick questions I’ve had several times so far. What about 30 out doors? Basically I’ve really only scratched the surface of debugging this thing. It may turn out to be completely simple or completely complicated. I’ve some ideas if it turns out to be complicated but I’m not really ready to abandon the idea that it may be simple. I find assembly hacking/debugging very fun. So I’m going to keep working on it in my spare time.

"Is there a soft cap of 30 outdoors? I’m not sure. I think it was Epigramx who said it but 'I can’t hack you better hardware.' While it would be cool to find some magical 30 fps lock that can be turned off I’m highly skeptical of that being the case. There are actually a few people who have reported getting 60 in the open world with skip fence on. So I’m pretty sure 30 fps outdoors is a hardware limitation."

You can see the hack working in this video.

User epigramx, who posted the hack on Reddit, adds that "Ironically the modification is already complete for a future system that would maintain 60FPS always but nobody can do that in practice yet... The 60FPS version of the hack is not as practical for current systems, or it's not a 'use and forget' thing. To use it you will normally unlock your FPS cap on Rivatuner so you can go 60FPS in a shrine with the hack and enjoy full 60FPS gameplay on normal gamespeed. However, since our CPUs are not fast enough to reach 60FPS in the open, we can't use the hack as it is and forget about it, so in practice it will have to be disabled for the outdoors."

Epigramx predicts that a couple CPU generations down the line we could see CPUs capable of consistent 60 fps performance. There's also the possibility that updates to Cemu could bring 60 fps within reach for current hardware, as the emulator becomes more efficient.

In the meantime, it seems likely this is just the beginning for the 60 fps hack. As epigramx mentions, the next logical step is to make it change the frame cap dynamically when entering shrines, or make it an in-game toggle, from 30 to 60, to keep performance smooth in the overworld and in shrines. You can follow along with the hack's updates from the Reddit thread here.