Well if you have it enabled in render settings already, then you have no need of shader GC. So then we would look at the shader for trouble.

Truth be told, the hair node is a mystery, i.e. it is not documented as to what it does and so we have to guess about what it does. From there we have to guess whether or not we actually want to use it.

Just because its name is Hair, does not justify its use. I have done almost no dynamic hair shading, so I can't tell you whether the hair node is helpful or junk. Certainly the Poser Skin node is junk. So is Velvet. If things seem unexpected with that node, I'd say there's a high likelihood it is junk.

Still - there may be some right and wrong things to do with it.

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Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)