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| AMD FSR 4.1.1 lossy2 improves moving foliage detail compared with the earlier lossy version. |
A community-made FSR 4.1.1 shader mod now ships a third DLL called lossy2, trained to match AMD's image quality more closely while keeping the same frame-rate boost — up to 25% faster in the developer's Shadow of the Tomb Raider benchmark.
PC gamers running Radeon RX 6000 and RX 7000 graphics cards have a fresh reason to tinker with their upscaling settings this week. The independent fsr4-shader-performance-overrides project, maintained by developer zgauthier2000, has published its October 19, 2026 release — and it introduces a brand-new lossy2 DLL that sits alongside the existing exact and lossy builds.
For anyone who hasn't been following the modding scene, the project replaces AMD's slowest FidelityFX Super Resolution 4.1.1 shaders with faster rewrites. The exact version preserves AMD's output byte for byte, while the lossy version skips work by running the neural network on alternate frames. The new lossy2 takes that same shortcut but swaps in freshly trained weights across six of FSR's twelve network layers.
What's new in the lossy2 DLL?
According to the official release notes, lossy2 was trained via knowledge distillation — essentially teaching the modified network to reproduce AMD's own output, frame skip included. The weights were built using the tooling from Durandal, the project's unreleased smaller-network research branch.
The headline result? Swaying foliage now looks dramatically closer to AMD's reference picture. On the test rig at 4K Balanced, lossy2 scored an error of 12.2 against AMD's 12.1 — a massive improvement over the original lossy build's 17.9. Thin wires in a slow pan also hold together far better, and firefly artefacts drop from 425 to 356 (or 128 vs. 182 with auto exposure enabled).
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| The developer's animated comparison shows how FSR 4.1.1 lossy2 preserves thin wires during slow camera movement. |
Performance: same 25% uplift, better image
Importantly, lossy2 doesn't sacrifice speed for that quality bump. In Shadow of the Tomb Raider at 4K Balanced on a Radeon RX 7800 XT under Linux, the new DLL rendered 18,784 frames at 121 FPS — virtually identical to the earlier lossy build and roughly 25% faster than AMD's stock shaders, which managed 97 FPS.
The GitHub release page also notes that the previous dll-2026-10-15 register cut has been removed from the lossy DLL. According to timing-kit data from over 30 reports, that should shave another 1.3% to 1.8% off upscaler time on RX 6000 cards, around 3% on the RX 7600, and about 1% on the Radeon 890M and Intel Arc B580.
The trade-offs you should know about
No mod is free of compromises, and the developer is refreshingly upfront about lossy2's weaknesses:
- Brightening lags 2–2.5× longer than lossy (1.54 frames behind vs. 0.64 on a bright area).
- Still images are 0.3–0.4 dB less accurate (43.9 dB vs. 44.2 dB).
- Heavy film grain is less stable when FSR's auto exposure is enabled.
- Ultra Performance mode is unsupported — lossy2 falls back to the original lossy network there.
The build was also trained only at 4K Balanced, so Quality and Performance modes run the weights unchecked.
How to get it
Both archives — one for RX 7000/RX 6000 cards, one for integrated graphics — now bundle three DLLs (exact, lossy, lossy2) and are available as a 5.6 MB .7z or an 82 MB .zip. You can grab them directly from the project's GitHub repository, where you'll also find the Linux launch-option method for avoiding DLL swaps altogether.
Installation is a simple file rename: locate amd_fidelityfx_upscaler_dx12.dll in your game folder (version 4.1.1.2740 required), rename it to .orig, then drop in the replacement. OptiScaler's overlay will show 4.1.1-lossy2-cyboman once it's running.
A word of warning
The developer is explicit: never use these DLLs in online games or titles with anti-cheat. Modified shaders and DLLs can be flagged as tampering, and that can get accounts banned. Single-player only. RX 9000 (RDNA4) cards are also explicitly unsupported since they run a different FSR 4 build entirely.
It's also worth remembering that the 25% figure comes from the developer's own benchmarks and hasn't been independently verified — gains will vary by GPU, game, resolution, and whether your CPU is the bottleneck.
For now, lossy2 is positioned as a stepping stone toward the full Durandal release. Until that lands, both lossy and lossy2 ship side by side, so you can A/B them yourself.
Source: NotebookCheck | GitHub Release | Release Notes