Microsoft's Xbox One backwards compatibility is almost taken from granted these days, but let's not forget the scale of the achievement here - even the standard Xbox One S model has the ability to outperform original hardware both in terms of CPU and GPU performance, with most titles sticking far closely to their frame-rate targets than they did on original hardware. But just how much faster could original Xbox 360 titles run if developer-imposed 30fps caps were removed? And is there a case for the games of today to include optional modes that unlock performance, only becoming fully exploited when running on the hardware of tomorrow?

It's a topic I've been considering recently having checked out how Ghost Recon Advanced Warfighter runs on Xbox One hardware after its recent back-compat release. It's an early Xbox 360 release originally released in March 2006, mere months after the launch of the console itself. It's also remarkable in that it mostly runs at 60 frames per second on Xbox One X, when performance analysis seems to demonstrate pretty conclusively that the original game has a 30fps target frame-rate. So what's going on here? Is Microsoft experimenting with its emulator and removing the original developer's frame-rate cap, and by extension, could more titles follow?

At first glance, you'd be forgiven for thinking that's the case, but based on a closer look at how the game operates on Xbox 360, the chances are that Microsoft's emulator is working exactly as it usually does and that GRAW's big increase in performance is something of a one-off. While the vast majority of gameplay on original hardware seems to run at 30fps - or frequently lower - there are little 'hiccups' in performance that see the game momentarily break free of its 30fps performance limit, usually accompanied by screen-tearing. The extra processing resources offered by Xbox One X seem to ensure that these edge-case scenarios on Xbox 360 become the norm, with the emulator's enforced v-sync taking care of the tearing in the process.

For its part, the Xbox One S also runs unlocked, but often sitting in a 40-50fps no man's land, shorn of the extra CPU and (especially) GPU power available on the X. As transformed as the game is on Microsoft's top-tier console, it is worth stressing that it's still not a locked 60 frames per second - larger scale areas and alpha transparencies can still cause issues. It's also more of a technical curiosity overall than a must-play back-compat experience - it's a fairly simple game overall and control is laggy to say the least, even running flat out at 60fps. As for how 60fps is possible under emulation beyond seemingly lifting the 30fps cap, it's likely that the game isn't exactly CPU heavy: AI is thin on the ground, environments are fairly sparse, and it is a cross-gen title of its era: GRAW also appeared on PS2 and the OG Xbox.

A look at Ghost Recon Advanced Warfighter's remarkable frame-rate boost on Xbox One, plus a wider view on potential forward compatibility.

But this concept of running Xbox 360 30fps titles at 2x frame-time is a compelling one, and the question must be asked - is there an argument for developers to include the option of an unlocked frame-rate in the games of today, not so much to accommodate the hardware of the here and now, but for the next-gen machines to come? We do actually have a handful of examples here from the Xbox 360 era that illustrate both the pros and the cons of doing so.

Take BioShock, for example - the original Xbox 360 release rather than the remaster. It does indeed feature a 30fps cap by default, but the option exists to turn it off. It also disables v-sync and was presumably included to offer an optional, PC-like experience. Performance is highly variable and the constant tearing is somewhat off-putting, but on Xbox One X, much of the experience plays out locked at 60 frames per second - it's certainly the best way to play that particular game. On the flip-side, we have Grand Theft Auto 4, which runs unlocked by default on Xbox 360, with performance sometimes careening wildly between CPU and GPU bottlenecks on Xbox One X when a 30fps cap would have helped the title immensely in delivering a more consistent experience (demonstrably so, bearing in mind the excellent results seen in Red Dead Redemption, where a frame-rate limit was added).

Going forward then, there is perhaps the argument that Microsoft might consider the option of removing performance caps for existing titles running on its next-gen hardware. Somewhat miraculously, the AMD Jaguar CPU clusters in the Xbox One family can now outperform the Xenon processor in original Xbox 360 hardware - based on the results of unlocked performance in GTA4, for instance. But the new wave of Xbox machines will offer a true generational leap in CPU power, along with another substantial improvement in GPU capabilities. I'm sure there may be many titles with technological limitations that prevent a workable 60fps, but let's remember that every back-compat title goes through a process where the game is tested by a team of 100 people, with tweaks made to the emulator if required. If 60fps works, it could be an option within the front-end similar to the graphics/performance selectable in current X-enhanced titles.

And moving beyond Xbox 360, there's also an interesting decision facing developers of today's titles - do they consider introducing features in the here and now with forward compatibility in mind? To a certain extent, it is already happening. Consider the growing support for dynamic resolution scaling (DRS). With the arrival of Xbox One X, we saw existing games including Call of Duty Infinite Warfare, Doom, The Witcher 3 and Halo 5 benefit tremendously from the extra GPU boosting performance and maximising resolution even before the release of their dedicated Xbox One X patches.

The Witcher 3 on Xbox One X concentrates on 4K resolution support, but there's also a new unlocked frame-rate mode. Its results aren't uniformly brilliant on today's hardware, but should be vastly improved on the console hardware to come.

But the question is whether the 30fps titles of today could also feature options to unlock frame-rate - just like BioShock on Xbox 360. Back in the day, Irrational Games would never have known that the title would eventually run so much better on next-gen hardware, but developers today will know that their current games will have access to more processing power on the Xbox consoles to come - and perhaps there is an opportunity here given that it is possible to make a number of informed guesses about the level of power new Xbox hardware may deliver.

But equally, it's worth remembering that some titles are simply hard-wired for 30fps - they're just designed that way. For example, Horizon Zero Dawn on PS4 Pro has a performance mode that doesn't unlock frame-rate, but acts to provide an absolutely rock-solid, zero compromise lock to its target frame-rate. Guerrilla's technology uses free CPU time within the 33.3ms per-frame budget to opportunistically stream in open world data ahead of time and unlocking Horizon's 30fps cap may have unforeseen effects elsewhere within the engine. That isn't to say that 60 frames per second isn't possible given a generational leap in CPU power, but it seems likely that it would require significant developer input - a dedicated patch, essentially.

Regardless, the results seen in Ghost Recon Advanced Warfighter are fascinating as a potential 'what if' scenario and with Microsoft pushing backwards compatibility in new, cool and exciting ways, perhaps the 9x resolution boost seen in specifically chosen X-enhanced 360 titles could also evolve to include a 2x temporal resolution increase on next-gen hardware. But whether developers would like to get involved with 'buried treasure' forward compatibility functions in the games of today remains to be seen. But at the very least, Xbox One X unlocked performance modes - like The Witcher 3's for example - offer an interesting option on today's games, but could really deliver the goods on the console hardware to come in the next couple of years.

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About the author

Richard Leadbetter

Richard Leadbetter

Technology Editor, Digital Foundry

Rich has been a games journalist since the days of 16-bit and specialises in technical analysis. He's commonly known around Eurogamer as the Blacksmith of the Future.

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