Introduction:

So there was a bug/issue which first appeared in version 2.4 in Septimont update where when Launching the game in dx11 would cause massive FPS studders/loss but the issue still exists as of version 2.6. I don't know the exact reason but This issue mainly occurred on iGPUs and Older GPUs. 

But an easy fix for it was to launch the game directly through the game files which launched the game with Dx12(DirectX 12) and fixed the problem. But recently with the 2.6 update, Kuro Games added FSR 3.1, XeSS 2, DLSS 4, etc. One of these features might have caused them to update the Shader Model or Feature Level.

Why DirectX 12 now doesn't work on these GPUs?

The game Logs show this, Main thing you should focus on is Max supported Feature Level: 12_1, shader model: 6.7, binding tier: 3 and Adapter only supports up to Feature Level 'SM6', requested Feature Level was 'SM6'. SM6 means Shader model 6, but as it said i already have SM6. So I suspect that wuwa now requires SM6.8 which I do not have support for (Ignore Microsoft Display Adapter) and hence causes the error shown in Image 1. Well SM6.8 requires special hardware and as Linus explained in the Video, it is not available on these older GPUs. 

That's why you now cannot launch the game in Dx12  which makes it default to Dx11 which then causes lag in septimont.

Solution(?): 

Additional Notes from @argon1ut(Discord)

1. DirectX 12 itself is backwards compatible. A GPU limited to Feature Level 12_0 or 12_1 can still run a DX12 game, provided the devs include fallback paths. Problems show up only when a game requires something from a higher Feature Level (like 12_2 / DX12 Ultimate). If the engine tries to call those features without a fallback, older GPUs simply fail to launch in DX12.,

2. Shader Models and Feature Levels are related but not identical:

   • Feature Levels = what the hardware can do (e.g., mesh shaders, VRS, RT).

   • Shader Models = what the HLSL language/compiler can expose.

   • In practice, new Shader Models (like SM 6.8) usually depend on modern hardware that also supports Feature Level 12_2, but they shouldn’t be conflated as the same thing.

3. With the introduction of FSR 3.1, XeSS 2, DLSS 4, etc., the game engine probably shifted to requiring newer DX12 Ultimate features or at least a newer Shader Model target. On GPUs stuck at FL 12_0/12_1 (common for older or integrated hardware), DX12 launch errors appear, forcing players back to DX11—and that’s where the Septimont stutter problem resurfaces. 

4. While it’s not standard practice, it’s also not uncommon for developers to raise a game’s SM requirement over its lifecycle. What’s rare, however, is that the WuWa devs didn’t include a fallback path. Typically, when games increase their SM requirements, it’s done in an optional capacity, either for higher-end settings or specific modes, rather than as a hard requirement. That suggests either it was done intentionally (unlikely given typical dev ops workflows) or, more plausibly, it was an oversight. This would be understandable, considering the complexity of integrating something like DLSS 4 into UE4.