First when I try to rotate my hdri it doesn't update in the IPR, I need to reload each time -> screenshot
And about velocity, if I enable motion blur render time increase a lot (5000 samples, adaptive sampling, error threshold : 0.001), without motion blur : 2'04 with motion blur : I've stopped at 12' !
And Gradient node doesn't work at all :/
If you have any suggestions or idea, thanks
Here is my scene :https://www.dropbox.com/t/abtEtCvB21nkHHsV