The diffuse color, and actual texture sampling happen in the fragment/pixel shader which as you can see is rather light. A baseline static color into diffuse phong model generates 38 pixel shader instructions and 33 vertex instructions. ie this Changing THAT material to blend_translucent instantly increases the vertex…
man something must be broken, i have done full Diffuse, Spec Gloss normals and detail normals on a vertex blend shader for 98 instructions. though you could easily drop down to 1 texture sample by putting both your grescale textures in to red and green of 1 texture, than masking out a channel of a texture coordniate and…
On this kind of material, the blend mode only needs to be translucent or additive, and you can then render it unlit. Put your colour into the emissive instead of the diffuse slot when you do this. The vertex shader shouldn't really be affected after you do this. I'd check your main node settings if something changes once…