Operating system: Windows-10-10.0.19041-SP0 64 Bits
Graphics card: GeForce GTX 1060 6GB/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 432.00
Broken: version: 2.83.5, branch: master, commit date: 2020-08-19 06:07, hash: rBc2b144df395f
Worked: (newest version of Blender that worked as expected)
Short description of error
When using a procedural normal map (multiple noise textures mixed with vertx colors as Factor), the viewport shading mode becomes very slow and is pretty much unusable for anything.
Exact steps for others to reproduce the error
WIth the attached scene, try navigating in the scene in viewport shading mode. It is very laggy for me. I need to be able to sculpt the mesh and see the textures at the same time...
The quick fix is to remove the normal input from the principled shader. Then everything is fine with the textures correctly displaying (with no bump map, but I don't need them unless I am making a render with Cycles).
The issue here is that every time I will want to make a render I have to go back to the shader and connect my normals maps back. There will come a time in my project when I forget to do this, and I will realize that once 2 days of rendering have passed...
A solution I am thinking of right now (I am going to submit a proposal on Right - Click - Select) : add a node that can act as a switch, to have different behaviors between eevee and Cycles. In my example it would look like : one input (the Normal) and two outputs : Cycles and Eevee, and I would plug Cycles only into the normal input of my principled shader, to basically make eevee ignore my normal map.