Cause of Complex Shader in Niagara System?

I’m having a hard time trying to optimize my shader for Niagara. I made a simple gradient material similar to default sprite material and the shader complexity shows green when I view from the material graph. However, as soon as I assign it to Niagara, the shader shoots up to red. Previously, I made a much more complex material with multiple Texture Lookup and it appears green. Even after applying it to Niagara. I don’t get how a much more complex material can be cheaper than a very simple material. I’ve tried converting it to Material Instance and it still heavy. Can anyone give explanation on why this happen? Thankyou