Spine or stiffness

[nksmfamjp]

What impact does this have on arrow performance? Is it more of a longbow performance thing?

[Dnk]

Define performance.

[nksmfamjp]

Accuracy, penetration, easy to work with when building arrows. . .

[Dnk]

If you are working within a manufacturer's specified range of arrow stiffness the for hunting your requirements will be met and exceeded.
It is easy enough to bare shaft tune so start with the heaviest most stiff shaft.

[nksmfamjp]

I'm sorry, I'm just not getting it. . .

As a performance requirement, I should have also said arrow velocity.

I still don't get how Spine, or bending stiffness affects an arrows performance.

[Pydpiper]

When an arrow leaves the bow it oscillates, flexes back and fourth rapidly. The "spine" will determine how fast that oscillation can be brought under control or weather it will have a negative effect on the flight characteristics.