We've tested The Callisto Protocol PC version, and we don't really have good news to share, as you might have already surmised from the headline.

　　As reported by fellow publications like Rock, Paper, Shotgun and DSO Gaming, The Callisto Protocol PC experience is literally ruined by stuttering due to a combination of causes, one of which is certainly the known Unreal Engine shader compilation issue.

　　To illustrate that, let's just look at the results of the built-in benchmark available in The Callisto Protocol PC. The first time I ran the testing tool at 4K with max settings, the result was a stuttering mess that averaged only 45,2 frames per second on a very powerful configuration (Intel i7 12700KF, RTX 4090). That's with AMD FidelityFX Super Resolution 2 upscaling activated on the Quality setting.

　　Curious to find out whether the stuttering was at least partially owed to the now-infamous Unreal Engine shader compilation issue, we closed the game and booted it up again to re-run the benchmark with the very same settings. The result was staggering: the test now averaged 75,7 FPS, a 67.4% increase, clearly because we had already run the scene and the shader compilation stuttering had mostly gone away.

　　To be clear, the optimization issues in The Callisto Protocol PC aren't limited to that. We tried switching off ray tracing, which can be enabled for shadows, reflections, and something called transmission (only after you've activated shadows), and the frame rate jumped again to 122,2 FPS, a 61.4% increase. The ray traced effects don't even look that much better compared to the rasterized ones, so we definitely recommend turning them off. It will not fix the dreadful stuttering, though.

　　Sometimes benchmark tools can yield very different results from what players actually experience during gameplay. It's not the case with The Callisto Protocol PC, however. While playing through the beginning of the game, we experienced entirely unacceptable slowdowns, even more so on such a powerful PC.

　　All it took was a pipe bursting or a new enemy appearing out of nowhere to literally tank the frame rate down to 20 or even 10 FPS for a few seconds. You don't have to take our word for it; just look at the footage below.

　　In one particularly egregious segment found in the latter video right above, the frame rate literally went below 10 frames per second. Then it went back up to over 100 FPS. We've never seen such a thing before, to be honest.

　　Granted, this game is optimized for AMD (it's even featured in the most recent Raise the Game bundle alongside Dead Island 2), and NVIDIA still hasn't released an optimized Game Ready driver for it. The extent of the issues currently found in The Callisto Protocol PC is simply too vast for these excuses to hold any weight, though. Besides, the game looks good, but it's no original Crysis, and even that one offered a better experience due to its constant, albeit low, frame rate.

　　It's also high time for the Unreal Engine shader compilation issue to be highlighted. Too many titles are plagued by the baffling decision to subject gamers to stuttering the first time they play through the game instead of just asking them to wait a couple of minutes while the shader cache is completed, as a few titles rightfully do.

　　Digital Foundry's Alexander Battaglia correctly feared this would be an issue for The Callisto Protocol PC. As it turns out, the game is one of the worst examples yet. The survival horror genre doesn't help, either, because most jump scares or surprises will be completely ruined by the frame rate suddenly tanking for no good reason. In closing, we'd recommend holding off on The Callisto Protocol PC until Striking Distance Studios improves optimization and tackles the shader compilation problem.