Recently I had been experimenting with atmospheres in vue 10. Usually I had just used presets that came with vue or i had bought seperatly. Now I have noticed that when I use GR or IR atmospheres they no longer do the dark prepass . Even scenes I had already done that first did a prepass and then then the second pass complete in one pass now. The finished images dont look (at least to me ) any different without prepass as they did with a prepass , but do appear to render quicker .Any idear what I may have done , and giving that i cant see any difference any way is anything to even bother about ?, though I would like to know what may have happend

Many thanks in advance for anyone able to help