URP Custom Function in Shader; Performance

I am using a few custom functions written in hlsl in shader graph to get the main light and all of the additional lights and shadows information.
Also considering that the additional light function has a for loop, how resource-intensive could it be for mobile?
PBR is using something similar to calculate the light out of the box, doesn’t it?

The whole purpose of using custom light was to create a toon shader for performance reasons. It would be ironic if it would be more intensive than PBR

Same question, makes me wonder.