Unreal Engine ray tracing stuttering in AMD RDNA 4 GPUs linked to Nvidia-optimized game code

[Alfonso Maruccia]

What just happened? Ray tracing was supposed to be faster and smoother on AMD's latest GPUs, yet some demanding games still struggle. A closer look now points to the real reason behind the disappointing performance. It's not just hardware limitations at play – engine choices and driver quirks are also shaping the experience.

Radeon RX 9070, Radeon RX 9070 XT, and other RDNA 4-based cards should perform much better than they have. AMD's latest GPU architecture promises improved ray tracing performance, but real-world results tell a different story.

According to user reports, Unreal Engine 4 (UE4) games experience severe stuttering on Radeon 9000-series cards when ray tracing is enabled. Digital Foundry replicated these issues in a recent YouTube video, confirming significant frame rate drops and stuttering in UE4 titles.

The problem is especially severe in Hellblade: Senua's Sacrifice, where stuttering can last several seconds and effectively freeze the game. Digital Foundry and the gaming community speculate that RDNA 4's poor ray tracing performance may result from a hidden AMD driver bug that disrupts shader compilation. However, a more detailed analysis by another YouTuber likely uncovered the true culprit.

The YouTube channel Tech Yes City examined RDNA 4 performance in Hellblade, The Ascent, and other ray tracing-heavy games – some of which stuttered even on Nvidia cards. It discovered both Hellblade and The Ascent are based on the UE4 framework but use a fork of the engine optimized for Nvidia cards called NvRTX. Developers chose NvRTX over the vendor-agnostic DirectX Raytracing implementation, effectively forcing Radeon 9000 owners to run sub-optimized code on their new GPUs.

Developers likely chose NvRTX because Nvidia markets its "RTX Branch of Unreal Engine" as an easy way to integrate advanced graphics technologies into games. NvRTX includes GeForce-exclusive features such as DLSS, DLAA, Nvidia Image Scaling, and real-time denoisers, along with other AI-based enhancements.

Despite RDNA 4's notable improvements, AMD is still playing catch-up with Nvidia in ray tracing. Tech Yes City noted that RT effects in Hellblade and similar titles can tank frame rates regardless of GPU, and few RX 9070 owners are likely enabling the feature anyway. The channel also uncovered a bug in AMD's graphics drivers, an issue that should be far easier to resolve with a software update.

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Unreal Engine ray tracing stuttering in AMD RDNA 4 GPUs linked to Nvidia-optimized game code

 

[redgarl]

Where is Tims to slam Nvidia for sabotaging AMD's performance?

Let's not act like we didn't knew about Gameworks sabotaging AMD performances for a long time. The examples are staggering, like The Witcher 3, Cyberpunk, Alan Wake 2, Wukong, Control... name them...

 

[yRaz]

This is also an issue on Intel cards. The unreal engine has turned into an unoptimized mess

 

[WhiteLeaff]

Who would have thought that Nvidia was to blame? Nobody ever knew that Nvidia has tentacles all over the gaming industry... Oh, well.

 

[SRB]

It works both ways, but developers cater to the Nvida crowd every time when the dust settles. I can't remember the game, but one that AMD actually got to optimize with all of the RDNA3 supported features enabled left the Nvidia 40 series in the dust. Needless to say, the outrage that came from the Nvidia camp was swift and large about an AMD sponsored title deliberately crippling Nvida cards. Turned out the optimizations simply took advantage of features AMD had that Nvidia didn't. A few months later, after some heavy Nvidia optimizations, the lead wasn't as big.

Point is, Nvidia has a history of writing software to deliberately lock out the competition in the name of "improvements", while publishers won't include AMD specific optimizations for just 10% of the market.

 

[redgarl]

Who would have thought that Nvidia was to blame? Nobody ever knew that Nvidia has tentacles all over the gaming industry... Oh, well.

If you were listening to Hardware Unboxed, good guy Nvidia never would have done something like that, however bad guy AMD obviously prevented the implementation of DLSS in Star Wars Jedi Outcast!

 

[redgarl]

This is also an issue on Intel cards. The unreal engine has turned into an unoptimized mess

It is not the engine, but the Nvidia proprietary driver used for Ray Tracing in Unreal Engine 4.

You know, when Nvidia is approaching you and asking you to implement RTX in Cyberpunk, Wukong, Alan Wake 2... in exchange for a monetary compensation...

 

[yRaz]

It is not the engine, but the Nvidia proprietary driver used for Ray Tracing in Unreal Engine 4.

You know, when Nvidia is approaching you and asking you to implement RTX in Cyberpunk, Wukong, Alan Wake 2... in exchange for a monetary compensation...

The engine was a mess without the proprietary nVidia nonsense that game developers put into it. The whole reason the nVidia specific version exists is that it allows game devs to optimize for the most common PC hardware since Epic can't optimize their own engine.

 

[pcnthuziast]

Unreal engine has been riddled with performance issues of every kind for years and through most iterations. It can produce some of the best visuals, but also has some of the worst performance of any engine that exists. I strongly dislike it for that reason and sadly, my favorite franchise, Borderlands, is always built on it.

 

[GeoffreyA]

Unreal engine has been riddled with performance issues of every kind for years and through most iterations. It can produce some of the best visuals, but also has some of the worst performance of any engine that exists. I strongly dislike it for that reason and sadly, my favorite franchise, Borderlands, is always built on it.

It's strange because Tim Sweeney and Epic's programmers have been and should be at id Software's calibre but are the opposite when it comes to efficiency.

 

[winjer]

Nvidia has become a pain for PC gamers.
What a **** company.

 

[Axeia]

It's strange because Tim Sweeney and Epic's programmers have been and should be at id Software's calibre but are the opposite when it comes to efficiency.

Because ID software's engine only has to run one or at most very few games. It can be optimized for that kind of task very effectively. If you were to say try to make a MMO or MOBA with it performance might be terrible. Anyone who played rage at launch (I did) ages ago can also tell you ID tech has had it's bad moments.

Unreal Engine is used for literally every genre of game (and more) with great variety between games within the same genre to boot. It's hard to optimise for say a side scroller, a turn based game and a MMO at the same time.
Unreal however manages to do all of them rather well and if performance is really awful it's rarely that the unreal engine itself is to blame. You'll often see a similar game from a different studio working fine.
Back in the day I always strongly preferred unreal engine games over CryEngine games which were often smaller in scope but performed far worse.

Can't say that at the moment I have a bias against any engine in particular. However with how easy Unreal engine 5 has made it to make a game with minimal knowledge the amount of poorly optimised ones is definitely on the rise.
It seems pretty easy to to get some asset packs and modify a game template a bit too mold into a generic but good looking game without doing any optimization yourself. It also seems what a lot of small studios or even individuals are doing lately, minimal effort slop but because it's UE5 and high quality assets it looks top notch but in every other way it can be very unpolished.

Imo unreal isn't poorly optimised it's just easy to use it wrongly if you don't know what you're doing. And the amount of developers that truely know what they're doing is slim.

 

[MasterAce]

Just pick any ”path traced” title to see nvidia optimized games

 

[wiak]

Always fun when people blame amd for nvidia's known gimpworks tricks

Where is Tims to slam Nvidia for sabotaging AMD's performance?

Let's not act like we didn't knew about Gameworks sabotaging AMD performances for a long time. The examples are staggering, like The Witcher 3, Cyberpunk, Alan Wake 2, Wukong, Control... name them...

there is a reason why amd hardware runs great on linux

 

[godrilla]

This is also an issue on Intel cards. The unreal engine has turned into an unoptimized mess

It's also a mess in Nvidia cards the latest Oblivion remastered can't run 100% smoothly with a 5090 and 9800x3d tweaked at 4k dlaa, frame gen at max settings.
The biggest benefactor in brute forced hardware is Nvidia. 6090 and or 7090 to play Unreal engine 5.0 games anyone?
In the end this approach only hurts Epic because gamers will not blame Nvidia but the unoptimized games that need a brute forced hardware to run it, by review bombing them and simply not buying them as well.

 

[yRaz]

It's also a mess in Nvidia cards the latest Oblivion remastered can't run 100% smoothly with a 5090 and 9800x3d tweaked at 4k dlaa, frame gen at max settings.
The biggest benefactor in brute forced hardware is Nvidia. 6090 and or 7090 to play Unreal engine 5.0 games anyone?
In the end this approach only hurts Epic because gamers will not blame Nvidia but the unoptimized games that need a brute forced hardware to run it, by review bombing them and simply not buying them as well.

I find it frustrating that games are designed to run on 90 class cards but actual hardware sales shows that barely anyone can play the games. Most people are playing Oblivion at 1080p30 with upscaling. I'm tried of devs making games for the top 2% of gamers and that's being generous.

I'm sure lots of people on this site/forum have high end hardware, but that's because we're enthusiasts and not representative of the actual demographic of gamers. Most people just want to play games and don't care about their hardware.

 

[GodisanAtheist]

Unreal 's whole deal, and the reason it's so popular as an engine, is because it's software as a service. Plug and play. As a dev you don't need a lot of software engineers to stand up and Unreal Engine game.

This has opened the door to a lot of devs who otherwise might not have been able to make a decent looking game, but the downside is no one making these games really knows how anything "under the hood" works with Unreal.

Nvidia having an RTX plug-in for Unreal is the whole system functioning the way it was designed. Plug and play.

Ideally, AMD should have their own plug-in with AMD optimized code for RT on Unreal, but AMD just doesn't have the resources or vision to be able to pull that kind of thing off.

As the industry coalesces around one singular engine, expect more of these shens going forward. Very few devs (id being the notable exception, and look how well their games run) actually purpose build their engines to suite the type of game they're looking to make.

 

[slavkoosy]

I'm tried of devs making games for the top 2% of gamers and that's being generous.

You should be more generous then. There were some 10,000 games released on Steam alone last year. Plenty of indie games that will run well and not favor specific hardware. Now, if you're only looking at AAA games from the big studios when you say "devs", then I can see your point. But that would ignore the fact that all those other games exist.

 

[wilfortune]

I can't remember the game, but one that AMD actually got to optimize with all of the RDNA3 supported features enabled left the Nvidia 40 series in the dust. Needless to say, the outrage that came from the Nvidia camp was swift and large about an AMD sponsored title deliberately crippling Nvida cards. Turned out the optimizations simply took advantage of features AMD had that Nvidia didn't. A few months later, after some heavy Nvidia optimizations, the lead wasn't as big.

Starfield launched like this, though I don't recall AMD leaving Nvidia "in the dust".

 

[yRaz]

You should be more generous then. There were some 10,000 games released on Steam alone last year. Plenty of indie games that will run well and not favor specific hardware. Now, if you're only looking at AAA games from the big studios when you say "devs", then I can see your point. But that would ignore the fact that all those other games exist.

Indie devs are more likely to lease an engine than develop their own. Unless you're talking about pixel art games or other nonsense, of all the indie games you're talking about few are worth playing. I'm a busy person, I get about 10-15 free hours a week to do with what I choose and most of the time, I'm choosing to catch up on sleep.

 

[yeahboii]

Is a classic move remember when tessellation ran like **** on AMD were games where they hid a bunch of tessellation inside geometry just to tank performance this ain't a new thing it's a NVIDIA classic help with development pay money make the software FK over the competition

 

[GeoffreyA]

Because ID software's engine only has to run one or at most very few games. It can be optimized for that kind of task very effectively. If you were to say try to make a MMO or MOBA with it performance might be terrible. Anyone who played rage at launch (I did) ages ago can also tell you ID tech has had it's bad moments.

Unreal Engine is used for literally every genre of game (and more) with great variety between games within the same genre to boot. It's hard to optimise for say a side scroller, a turn based game and a MMO at the same time.
Unreal however manages to do all of them rather well and if performance is really awful it's rarely that the unreal engine itself is to blame. You'll often see a similar game from a different studio working fine.
Back in the day I always strongly preferred unreal engine games over CryEngine games which were often smaller in scope but performed far worse.

Can't say that at the moment I have a bias against any engine in particular. However with how easy Unreal engine 5 has made it to make a game with minimal knowledge the amount of poorly optimised ones is definitely on the rise.
It seems pretty easy to to get some asset packs and modify a game template a bit too mold into a generic but good looking game without doing any optimization yourself. It also seems what a lot of small studios or even individuals are doing lately, minimal effort slop but because it's UE5 and high quality assets it looks top notch but in every other way it can be very unpolished.

Imo unreal isn't poorly optimised it's just easy to use it wrongly if you don't know what you're doing. And the amount of developers that truely know what they're doing is slim.

Agreed. UE covers a wider span than id's, and the ease that a game can be put together is both a positive and negative. When the developers put the effort and know what they're doing, the results are good; for example, Expedition 33 runs fair without stuttering, despite extensive effects. Having said that, I think the engine's architecture is more demanding than others. In benchmarks, it tends to show.

 

[yRaz]

Agreed. UE covers a wider span than id's, and the ease that a game can be put together is both a positive and negative. When the developers put the effort and know what they're doing, the results are good; for example, Expedition 33 runs fair without stuttering, despite extensive effects. Having said that, I think the engine's architecture is more demanding than others. In benchmarks, it tends to show.

there is a youtube series from a game dev about common mistakes made in unreal engine. One of them is that Unreal often asks the GPU to render things that you can't see, say a building is in the way, it will render everything the building is blocking if you aren't careful. I see issues like that as something fundamental that should be taken care of by the unreal devs, not the devs using the engine to make games.

 

[GeoffreyA]

there is a youtube series from a game dev about common mistakes made in unreal engine. One of them is that Unreal often asks the GPU to render things that you can't see, say a building is in the way, it will render everything the building is blocking if you aren't careful. I see issues like that as something fundamental that should be taken care of by the unreal devs, not the devs using the engine to make games.

Yes, culling is a technique going back to "ancient" engines.

 

[wiyosaya]

So, this is because of lazy developers that don't want to test what GPU they are running on? The test cannot be that difficult. Though having to optimize for AMD and Nvidia GPUs means more work and, perhaps, deadlines not met.

IMO, its shortsightedness.