It was going ok but then started to render the frames at twice the length of time again. I think I have figured it out though? The Backburner Server on the machine gave an error saying it couldn't read or write to the UHD file. SO I think the frame was computing the GI from scratch. Hence taking twice as long...
When I send frames and load in the UHD should the After Render box be as per the attached. So 'Save to File'? That is how I sent it so maybe some machines are trying to save to it at the same time and crashing? Should it be set to Discard?
Cheers.
