Irradiance From File Takes Longer?

[Teriander]

Hi,
I have a scene that's using Irradiance and Light Cache to render. When I use Irradiance Map set to "Single Frame". I get about 5 mins per frame. Which is fine. But when I switch to "Multiframe incremental",save out a pass of ever Nth frame which creates a file that is about 8mb in size, then turn off Light Cache and switch my "Multiframe incremental" to "From File", my render time goes up to an hour. For the same frame.

Why is my render time going up so high when switching to From File? I haven't seen this issue before.

Vray v.2.40.04


::Update::
Ok, it appears it has something to do with the VRay-FogEnvironment. Has anyone had issues pre-calcing this before? Basically my issue is:
Using VRay-FogEnvironment + Irradiance Map + Light Cache and "Single Frame" my render time is 5mins. Using Multiframe Incremental my render time is over an hour. With VRay-Fog turned off, less than 1 min for both Single and Multiframe. Any suggestions?

[Neilg]

Render the fog as a separate pass.
When you do it as a single frame, the GI speeds up the fog pass. when you load from file, it seems to do it brute force or something. I found it odd too, so now my fog passes get rendered separately with reflections switched off and in single frame GI mode (the vrayatmosphere pass wont flicker, no matter how low you drop the settings - but it will speed it up a lot)

[Teriander]

Ok cool, thanks. I'll give it a try.

[Macker]

Sounds very similar to my issue; http://forums.chaosgroup.com/showthr...Frame-slowdown