Thanks SittingBlue ! This test is, I think really usefull for all Vue users, and I'll keep your rendering chart. I notice that a render with Best Quality Threshold but with only 2 rays of antialiasing has approximatively the same result than a 75% quality threshold with 25 rays antialiasing. In fact, it looks like improving Quality Threshold makes better result than improving number of rays... Now the question is what makes the rendering time grow the most : Threshold Quality or Ray for Antialiasing ? A question now comes to my mind : did you took a look at the rendering time for these pictures ? What's the range of time between the first picture (fastest/2 rays) and the last one (best/25 rays) ?