I'm also confused by the assertion that IC=0 is something like saying IC is off.

That's when IC is most on. The Irradiance Cache numerical value is how correct you want the result. If you want it 0 that means you want every bit of speed in exchange for total crap in the results. That was the fastest use of IC, not IC=off.

Previously, to turn IC off, you set IC=100. By doing that you were saying you wanted 100% accuracy and did not want IC in use because IC contributes to speed and inaccuracy, simultaneously.

Now there is a new switch to turn IC on and off separate from the IC value. The IC value has also probably changed in interpretation, since adjustments were made in the renderer with and without IC.

It may be that IC=0 no longer means quite the same thing. But if you want that kind of fastest-possible-I-don't-care-what-it-looks-like, you should be using the D3D Render Firefly dialog anyway.

---

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)