ShaderCompilers take 100% C drive performance - very slow

Development Platform & Builds
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When compiling shaders, UE shadercompilers take 100% of my nvme Cdrive thats still fairly empty (500Gb free). The 16 core cpu is barely used, the 64gb memory also still lots free.

This process really cripples performance of the win11 systeem overall.

I tried making a directory symbolic link for the UnrealShaderWorkingDir folder and point it to a nvme D drive with lots of space. BUt, UE deletes those directories before a new shader compilation batch process is started.

My laptop with the same setup (win11, 2 nvme drives, same folders etc) doesn’t have this problem.
Any suggestion what can cause this and/or how to point the UnrealShaderWorkingDir to my D drive?

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Hello there @maxbrown!

For this scenario, we cannot change shader compiler folder’s directly, but we can control where they end up stored, at the Derived Data Cache.

All information related to DDC and how to manipulate it can be found in the following community guide:

Alternatively, there’s a manual method to alter how DDC data is saved, which proved useful in a similar scenario to yours:

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thanks for the reply. Will test tomorrow

1 Like
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Just tested this and two extra directories are made in every project (LocalDerivedDataCache & DerivedDataCache) but still the shader compiling process takes 100% of the C drive performance. Maybe I have to re-install UE completely on this desktop although a Verify check was done.

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Hello again!

That would be a good approach. I would suggest a full uninstall/reinstall of all Epic software:

  • First, uninstall the engine, launcher, asset packs, etc
  • Next, open the registry directory HKEY_CURRENT_USER\Software\Epic Games\Unreal Engine\Builds, and delete any build entries
  • Finally, delete the folders %userprofile%\AppData\Local\UnrealEngine and %userprofile%\AppData\Local\UnrealHeaderTool
  • After that, no elements related to UE should be left in your system
  • Now, reinstall UE launcher from scratch, and only add the latest version of the engine
  • After the process is complete, test compiling shaders again

As alternative solutions, in another thread with a similar problem, it was suggested to alter the priority of the process for shader compilation, reinstalling all elements from Visual Studio 2022, as well as setting an UE exception for antivirus. I would not recommend that last step, though. All details can be found here: