Rectangle Light Directional is slow as hell

[miguelortega]

why do the render times increase so dramatically by increasing the Rectangle Lights directional slider?
its reallllllllly slow.

any tips?

[vlado]

It's hard to say without more information. Can you post a simplified scene?

Best regards,
Vlado

[miguelortega]

its in all our scenes with fog. before we send anything, is there anything we should be looking at that may slow it down when using directional?
if i create a single light, a plane, and a sphere and use vray environment fog with fog samples at around 180
the render times with directional set to 0 = 1:47
render time with directional set to 1 = 2:22 and is really noisy

we havent loaded any of the latest builds, but were also wondering if there have been any improvements to the fog in terms of noise in the later releases.
we are cranking up our subdivs to 180-200+ and still getting a lot of noise in general.

thanks Vlado!

[ivaylo.ivanov]

Will see what we can do about this. The only work-around for the increased noise is to increase also the "light cut-off trreshold" I think. You will get a biased result, but even with small values (like 0.001), you are getting it anyway...