I remember when I got my first computer, and I downloaded Fractint and would sit and watch as it rendered images, one slow line at a time. And I remember my early days of using Ultra Fractal, when new coloring methods would be written, some of them were ridiculously complicated and would render one slow line at a time.
Over the years, technology has advanced, processors have gotten faster, and I can open up some of those old parameters and have them appear in a few quick seconds. But somehow, I always still seem to end up staring at my monitor, transfixed, as an image appears one slow pixel at a time. Sometimes it's because I'm doing deep zooms, that get into arbitrary precision. Sometimes it's lots of layers. Sometimes it's ever-more elaborate coloring methods.
This tiny snippet is probably the slowest combination of things I've tried so far. It's a Mandelbrot zoom, with Extended Precision, fairly close to the boundary (so needing lots of iterations to avoid blank gaps), and with my own parametric coloring in a particularly slow configuration. At 400 x 400 pixels, this took four hours to render. I wanted to do a test of whether it would look like I expected, so as to be used in a larger, several-layered image. Unrendered, it dissolves into a mass of crunchy pixels.
So now I'm wondering, is it worth doing the somewhat larger render of the image that this is a component of? It looks like the guilloche-pattern effect is working the way it's supposed to. If I go by my on-screen working version, the colors and layers are okay. Render time estimate is somewhere between 850 and 900 hours. That's more than a month, assuming it doesn't slow down a lot when it gets near the minibrot in the middle.
Well, I've started it. It can mutter away in the background while I'm thinking of other things.