Variable Rate Shading, or VRS, is an important piece of graphics technology that PC games have largely ignored for the past three years. It works on all modern AMD and Nvidia graphics cardsand it has a simple goal: to improve performance by as much as 20% without any noticeable degradation in image quality.
Sounds great, right? There’s a reason you probably haven’t heard much about it. The last few years have focused on Nvidia’s Deep Learning Super Sampling (DLSS) and AMDs FidelityFX Super Resolution (FSR) as the performance-saving champions of the modern graphics era. And while they offer the best bang for the buck from the game developer, VRS is an equally impressive tool that is woefully underused.
VRS is not new — Microsoft’s blog post the announcement of the feature in DirectX 12 is over three years old. If you are unfamiliar, VRS changes the resolution at which shaders are applied within a scene. It doesn’t change the game’s resolution; VRS simply allows adjacent pixels to share a shader instead of the GPU doing unnecessary work.
For example, if a corner of a scene is shrouded in shadow without much detail, your graphics card won’t need to calculate the light, color, and texture values for each pixel. Grouping them together can save some hassle – four pixels in a 2×2 grid can have extremely similar shade values, so VRS starts to optimize performance by calculating just one shader and applying it to the rest of the grid . The size of the grid is the shading rate, and more pixels in a grid means a lower shading rate.
That small change can make a big difference in performance. In Gears Tactics at 4K, for example, VRS offered a 22.9% increase in my average frame rate. That’s the best example, but Resident Evil Village also showed a 9.8% increase in my average frame rate, while Hitman 3 offered a solid 8% increase. And the idea behind VRS is that it should be indistinguishable when enabled, essentially providing free performance.
There are only a small number of games that support VRS on PC, despite being over three years old. I’ll cover that issue later in the column, but the more pressing issue is how VRS is used in the few games that support it.
There are two buckets for VRS: one that makes it look like a revolutionary piece of kit that offers free performance, and another that makes it look like a feature that hurts more than helps.
Microsoft has two levels of VRS in DirectX 12 Ultimate: Aptly named Tier 1 and Tier 2. Tier 1 VRS is the most common technique you’ll find in games, and that’s the crux of the problem. This level doesn’t deal with individual pixels, instead applying different shading rates to each draw call. For example, when there is a call to draw background items, they can have a shadow rate of 2×2, while items drawn in the foreground have a shadow rate of 1×1.
Tier 2 VRS is what you want. This is much more detailed, allowing the developer to shade inside a draw. That means that part of a model could have a shadow speed of say 2×2, while a more detailed area on that same model could use 1×1. Tier 2 VRS is ideal, allowing the developer to focus on the details that matter to squeeze out every ounce of performance.
The problem: Even among the small pool of games that support VRS, most only use Tier 1. Resident Evil Village, the most recent game I watched uses Tier 1 VRS. You can see above how that affects image quality, where you can discern pixels in the snow while Tier 1 VRS puts everything together a few feet away from the camera.
Compare that with gear tactics, that supports Tier 2 VRS. There is a slight difference in quality when zoomed in to almost 200%, but it looks much nicer than Tier 1. You can see a difference when the two are side by side and zoomed in, but put these two frames one after the other in a blind test, and you wouldn’t be able to see a difference. I certainly couldn’t.
Free performance for virtually no loss in image quality is a big deal, but on PC at least VRS isn’t as much in the conversation as it should be (let alone the discussion between Tier 1 and Tier 2). Even after moving Gears Tactics and Gears 5 to Tier 2 VRS, developers haven’t jumped on the performance-saving train. Instead, VRS has mainly focused on the limited power budgets of consoles, and there is one particular console that holds back the feature.
The reason VRS comes in two flavors is that Tier 2 requires specific hardware to work. Nvidia’s RTX graphics cards and AMD’s RX 6000 GPUs have hardware support, just like the Xbox Series X. Older graphics cards and not the PlayStation 5† Instead, they use a software version of Tier 1 VRS, if it is already available in the game.
Developers working on cross-platform titles usually focus on the lowest common denominator, which means Tier 1 VRS. Only a few developers have done their best to support Tier 2 VRS on supported hardware (id Software uses Tier 2 VRS on Eternal doom for the Xbox Series X, for example), but the vast majority of modern AAA games do not support VRS or use this Tier 1 approach.
As Gears Tactics shows, a good Tier 2 implementation from the developer provides the best image quality and performance. It is true that DLSS and FSR provide an easy solution for developers to improve PC game performance. But a good Tier 2 VRS can represent a boost of about 20% for barely any difference in image quality, and that’s too good to ignore.
This article is part of ReSpec – an ongoing biweekly column featuring discussions, advice and in-depth reporting on the technology behind PC gaming.