Procedurals don't incur the "loading texture" time that big images chew up, so there is that savings. But in general, extremely complex procedures like this that have to use a lot of "noise" nodes (not one or two, but eight or ten) are actually somewhat slower than using an image. However, unless you're going to zoom the iris to 1000 pixels, you're not going to notice any speed difference. 

I can't see it providing any benefit for animation, unless you want to actually animate the texture itself, which is certainly possible. Many cool sci-fi effects could be done by altering the parameters to the shader in an animation.

Kurome - thanks. Yes I must figure out how to get the fibers to do more complex things - clumping, and more individual twisting. There are over 720 fibers in that image. Getting each of them to do its own thing without giving it it's own node(s) is a mind bender.

---

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)