I understand.

All I did was importing the same scene file into 10.5 and checked the pointlight settings (softness and power) and the atmosphere model.
In this case it is the standard model with GI. In Vue Infinite 5 and 10.5 PLE.
I double checked it again to be really sure.

I understand that 10.5 & 5 not really could be compared.. but this project is faster rendered in 5. Why? Maybe because 10.5 is way better in realism and that maybe increased the render time?

What else could I check in 10.5 PLE? 

more VUE Infinite on -> javildesign.com